With motor started and driving, brakes act and feel like no power. On air pressure cover service manual # is 2820134. Fluid is good.

Unless you have a power steering assisted brake booster more common with a diesel, you may have a new pump issue like the flow control valve in the pump or air in the system yet, check for air bubbles or a milky looking fluid and the correct fluid. Try in a parking lot out of the way of traffic to put in neutral while moving,rev the motor slightly and brake as you would when the PS assist stops,by revving the motor just off idle this will increase the PS pressure it should act normal if it's a flow control issue and if the pump is capable of producing the correct pressure.

GRAVITY BLEEDING CLUTCH HYDRAULIC CIRCUIT

1. Verify fluid level in brake master cylinder. Top off with DOT 3 brake fluid as necessary. Leave cap off.

2. Raise vehicle on hoist.

3. Remove bleed port protective cap and install suitable size and length of clear hose (4) to monitor and divert fluid into suitable container.

4. Open up the bleed circuit by turning the thumb screw (3) counter clockwise this will start the air purge and fluid fill process.

5. Lower vehicle, but only enough to gain access to and fill the brake master cylinder. NOTE: Do not allow clutch master cylinder to run dry while fluid exits bleed port.

6. Top off brake master cylinder fluid level while air is purged and fluid drains from bleed port. Continue this until no air bubbles are seen and a solid column of fluid exists.

7. Close hydraulic bleed circuit, remove drain hose and replace dust cap on bleed port.

8. From driver's seat, actuate clutch pedal 60-100 times.

9. Apply parking brake. Start engine and verify clutch operation and pedal feel. If pedal feels fine and clutch operates as designed, stop here. If pedal still feels spongy or clutch does not fully disengage, excessive air is still trapped within the system, most likely at the master cylinder.

10. Top off brake master cylinder fluid level with DOT 3 brake fluid as necessary.

POWER BLEEDING CLUTCH HYDRAULIC CIRCUIT

1. Remove reservoir cap and connect bleeder cap to reservoir. NOTE: Use Bleeder Cap/Modified reservoir cap adapter Snap-on #901-059 or equivalent.

2. Connect service filling machine to bleeder cap. NOTE: Use Service Filling Machine/Brake power bleeder Brake power bleeder or equivalent.

3. Service filling machine should be pressurized to at least 2.5 bar (36 PSI).

4. Remove dust cap from bleeder valve and connect the transparent bleeder hose to bleeder valve.

5. Place the other end of hose in the bleeder container to capture the used fluid. The end of the hose MUST be submerged in the DOT 3 brake fluid.

NOTE: Use Bleeder Container To capture hydraulic fluid and Transparent Bleeder Hose To route fluid to container.

6. Turn on the service filling machine.

7. Crack open the bleeder valve (3).

8. Allow fluid to flow out of bleed port until no more air bubbles can be seen in the transparent bleeder hose.

9. Once fluid is free of air bubbles; make 15 quick actuations between clutch pedal stop positions.

10. Close the bleeder valve and disconnect the service filling machine.

11. To remove remaining air, actuate pedal 10 times slowly between pedal stop positions.

12. Check clutch pedal to see if vehicle is properly bled.

13. If vehicle is not properly bled, repeat procedure.

14. Remove bleeder cap from reservoir and replace reservoir cap.

15. Disconnect transparent bleeder hose from bleeder valve and replace dust cap.

Given the age of your vehicle and that you do not see any fluid loss, the most likely reason for the brake peddle act this way is because of an internal leak in the master cylinder.
The master cylinder has a piston the operates the brakes when pressure is applied from the peddle. Basically, this piston provides and maintains the fluid pressure because of rubber "O" rings or seals. If the seals are going bad (due to age and wear) the fluid will bypass the piston but still stay in the cylinder and reservoir.
The master cylinder can be rebuilt or new one cost $65-$120 depending on if you have anti-lock brakes. Here is a link to a supplier (with part photos) (Click Here) Labor about 2-3 hours.
J

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I will explain it to you the best way i know how..take the cap off of the master cylender, make sure its full of fluid, leave cap off, get a partner. when you bleed brakes you always start at the wheel farthest away from the master cylender and work your way to it, so start at the rear passengers wheel, have your partner pump the brake pedal 12 or so times, and hold pressure against it ( TELL THEM NOT TO LET UP, UNTIL YOU TELL THEM) crack the bleed plug, let air/fluid out, re snug the plus.( now they can let off.. if they let off of the pedal before the bleeder is tight, it will pull air in the system, and you will hafta start all over again.) Do this a few times, until you get a steady flow of fluid, with no air bubbles. After this one is bled, top back off the master cylender, then go to the back Drivers wheel, do process over again, between every wheel top off master cylender. then go to passengers front, and then finally drivers front... hope i explained this good enough for you to understand.. and if you have never messed with brake fluid before DO NOT let any of the fluid touch the paint on your vehicle, it will strip it off. hope this helps

try this ABS bleeding procedure:

WITHOUT TECH 1® OR T-100®

Do not place your foot on the brake pedal through this entire procedure unless specifically instructed to do so.
This method can only be used if the ABS warning lamp is not illuminated and not DTC's are present.

1. Remove your foot from the brake pedal.
2. Start the engine and allow it to run for at least 10 seconds while observing the ABS warning lamp.
3. If the ABS warning lamp turned ON and stayed ON after about 10 seconds, the bleeding procedure must be stopped and a Tech 1® must be used to diagnose the ABS function.
4. If the ABS warning lamp turned ON for about 3 seconds, then turned OFF and stayed OFF, turn the ignition OFF .
5. Repeat Steps 1-4 one more time.
6. The entire brake system should now be bled by following the guide or pressure bleeding procedure.

Manual Bleeding
See Figure 3

1. Clean the master cylinder fluid reservoir cover and surrounding area, then remove the cover.
2. Add fluid, if necessary to obtain a proper fluid level, then put the reservoir cover back on.
3. Prime the ABS hydraulic modulator/master cylinder assembly as follows:
   1. Attach a bleeder hose to the rearward bleeder valve, then submerge the opposite hose end in a clean container partially filled with clean brake fluid.
   2. Slowly open the rearward bleeder valve.
   3. Depress and hold the brake pedal until the fluid begins to flow.
   4. Close the valve, then release the brake pedal.
   5. Repeat Steps 3b-3d until no air bubbles are present.
   6. Relocate the bleeder hose to the forward hydraulic modulator bleeder valve, then repeat Steps 3a-3e.
   
   
4. Once the fluid is seen to flow from both modulator bleeder valves, the ABS modulator/master cylinder assembly is sufficiently full of fluid. However, it may not be completely purged of air. At this point, move to the wheel brakes and bleed them. This ensures that the lowest points in the system are completely free of air and then the assembly can purged of any remaining air.

Fig. Fig. 3: ABS hydraulic modulator/master cylinder bleeder locations

1. Remove the fluid reservoir cover. Fill to the correct level, if necessary, then fasten the cover.
2. Raise and safely support the vehicle.
3. Proceed, as outlined in the following steps, to bleed the wheel brakes in the following sequence: right rear, left rear, right front, then left front.
   1. Attach a clear plastic bleeder hose to the bleeder valve at the wheel, then submerge the opposite hose end in a clean container partially filled with clean brake fluid.
   2. Open the bleeder valve.
   3. Have an assistant slowly depress the brake pedal.
   4. Close the valve and slowly release the release the brake pedal.
   5. Wait 5 seconds.
   6. Repeat Steps 7a-7e until the brake pedal feels firm at half travel and no air bubbles are observed in the bleeder hose. To assist in freeing the entrapped air, tap lightly on the caliper or braking plate to dislodge any trapped air bubbles.
   
   
4. Repeat Step 7 for the remaining brakes in the sequence given earlier.
5. Carefully lower the vehicle.
6. Remove the reservoir cover, then fill to the correct level with brake fluid and replace the cap.
7. Bleed the ABS hydraulic modulator/master cylinder assembly as follows:
   1. Attach a clear plastic bleeder hose to the rearward bleeder valve on the modulator, then submerge the opposite hose end in a clean container partially filled with clean brake fluid.
   2. Have an assistant depress the brake pedal with moderate force.
   3. Slowly open the rearward bleeder valve and allow the fluid to flow.
   4. Close the valve, then release the brake pedal.
   5. Wait 5 seconds.
   6. Repeat Steps 11a-11e until no air bubbles are present.
   7. Relocate the bleeder hose to the forward hydraulic modulator bleeder valve, then repeat Steps 11a-11f.
   
   
8. Carefully lower the vehicle, then check the brake fluid and add if necessary. Don't forget to put the reservoir cap back on.
9. With the ignition turned to the RUN position, apply the brake pedal with moderate force and hold it. Note the pedal travel and feel. If the pedal feels firm and constant and the pedal travel is not excessive, start the engine. With the engine running, recheck the pedal travel. If it's still firm and constant and pedal travel is not excessive, road test the vehicle and make sure the brakes are operating properly.
10. If the pedal feels soft or has excessive travel either initially or after the engine is started, the following procedure may be used:
    1. With the Tech 1® scan tool, Release then Apply each motor 2-3 times and cycle each solenoid 5-10 times. When finished, be sure to Apply the front and rear motors to ensure the pistons are in the upmost position. DO NOT DRIVE THE VEHICLE.
    2. If a Tech 1® scan tool is not available, remove your foot from the brake pedal, start the engine and allow it run for at least 10 seconds to initialize the ABS. DO NOT DRIVE THE VEHICLE. After 10 seconds, turn the ignition OFF . The initialization procedure most be repeated 5 times to ensure any trapped air has been dislodged.
    3. Repeat the bleeding procedure, starting with Step 1.
    
    
11. Road test the vehicle, and make sure the brakes are operating properly.

That is a classic sign of a bad brake master cylinder.

1 Siphon off the old brake fluid in the master cylinder reservoir under the hood.
2 Fill the reservoir with new brake fluid (don't reuse old fluid as it holds moisture and will corrode your brake system).

3 Start with the brake farthest from the Master cylinder, usually rear wheel, passenger side. Pull off the rubber cover on the bleeder valve. Attach the aquarium air line to the nipple on the bleeder.

4 Have your assistant pump the brake pedal up and down 3-4 times, then hold the pedal down fairly hard.
5 Open the bleeder, let fluid flow out through the air line into a waste container. (preferrably a clear bottle so you can see any air bubbles escaping the system). When the fluid stops and your assistant's foot hits the firewall (brake pedal all the way down), close the bleeder valve immediately!
6 Go to step #4 above and drain more fluid out of the bleeder valve until clean fluid comes out. Check the master cylinder every time and top it up as necessary. This procedure uses lots of fluid.

7 Now move to the rear brake on the driver's side. Go to step #4 and repeat the same procedures above until clean fluid comes out of the bleeder valve and no bubbles.
8 Next is the front brake, passenger side, same procedure. Then the drivers side and the same procedure.
9 When finished check for any leaks, remount rubber covers on the bleeder valve nipples. Remount all wheels, re-torque lug nuts after 50-100 miles of driving.
10 Start vehicle and depress the brake pedal. It should feel much less spongy than before this procedure. If not, there is air in the system, start over. Bleed everything again.
Note: if you assistant releases the brake pedal before you can close the bleeder valve then air will be introduced into the brake lines. This is no good! Before you start tell your assistant you will tell him/her PUMP, HOLD DOWN, RELEASE commands.

That's it, you're done. Congratulate yourself on saving some cash instead of handing it over to a mechanic.

cat converter check that..

Sounds like it is starving for fuel...the other guys sound right...check your fuel filter and fuel pressure...if the filter is nearly stopped up the pump would build pressure which would "push" past the filter and make it feel more powerful...then as the pressure drops it starts to starve again until the pressure builds up enough. Also, with the vehicle parked and running, get someone to rev it up while you feel the air coming out of the exhaust...if it isn't a good amount of pressure coming out of the tailpipe, your converter may be stopping up. be careful not to get burned by the exhaust though.