I have a 1994 toyota pickup 1/2 ton, and i have to press the gas pedal when i'm on stop light, because if not the engine goes off

1 First you will need to purchase a blank Toyota transponder key. You can do this from the dealership, a locksmith, or an online source such as eBay. Once you have the key, take the blank key and the master key to a locksmith that he or she can duplicate the key. This will be much cheaper than the dealership.

2 Now that you have the newly cut key and the master key, you can program the Toyota transponder key. Sit in the driver's side of the Toyota vehicle. Press and release the brake and gas pedal simultaneously.

3 Insert the master transponder key. Do not turn it. Push and release the gas pedal 5 times within at least 15 seconds of inserting the master key.

4 Press and release the brake pedal 6 times within 20 seconds of completing step 3, then remove the master transponder key.

5 Insert the newly cut transponder key into the ignition, but do not turn. Press the gas pedal once.

6 Wait up to 2 minutes or whenever the security light on the dashboard turns off. Once the light goes off, remove the new transponder key and press the brake pedal once. The new transponder key should now be programmed. Test the key by attempting to start the engine. If the engine does not start, repeat the steps above.

Check the throttle body cable, there should only be approx. 1/4" play in it, you may have a vacuum leak as well, check all hoses and make sure they are all tight. It could be fuel injector related (dirty/ clogged) the same applies to your throttle body.

have you or anybody at pep boys changed the igniter and coil. if not try to find a used igniter and coil to test with, they're pricy. If it works replace with new parts.

it may be : the brake booster is lack of vacuum pressure and can't supply enough force when you push the brake pedal. we supply all kinds of Toyota brake boosters : feel free to contact if any interest

does thr engine rev upwhen started than idels back down.try idel control switch and map sensor

It can be issue with fuel pressure,its low or the problem relates to faulty spark plugs.
There are few troubleshooting steps to confirm the problem.I suggest you few help links,with complete troubleshooting and solution for these types of issues.

1991 Toyota Trecel: Engine Starts fine but dies when gets Warm? http://whatisbyme.blogspot.in/2012/05/1991-toyota-trecel-engine-starts-fine.html

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1994 Toyota Pickup: Starts fine but dies in few seconds?

http://howtobyme.blogspot.in/2012/05/1994-toyota-pickup-starts-fine-but-dies.html

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1994 Lexus ES300: Engine Idles Rough and Dies? http://whatisbyme.blogspot.in/2012/05/1994-lexus-es300-engine-idles-rough-and.html

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Stalls And Dies At Stop Sign? http://www.howtobyme.blogspot.com/2012/07/stalls-and-dies-at-stop-sign.html

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Car dies when gas pedal is pressed? http://schematicsdiagram.blogspot.com/2011/12/car-dies-when-gas-pedal-is-pressed.html

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These help links will help you to troubleshoot and solve the issue.
Thanks.

If you're not losing any brake fluid then it sounds to me as though the master cylinder is bleeding fluid between to two chambers allowing fluid to pass from one to the other which would decrease the pressure on one of the lines leading to the proportioning valve, thus setting off the 'brake' light.

Orrrrr,

IF it does NOT have the hydroboost system the following steps MAY help diagnose if it's a booster problem.

(Copied and pasted from a youtube comment)

Test 1) 1. Start the car 2. Let it idle for 2 minutes 3. After 2 minutes turn off the car 4. Pump the brake pedal 3 times 5. The pedal should rise every time if it does then the Booster and Check valve are OK 6. If the pedal doesn't then the is an issue with the either one, run tests 1 and 2.

Test 2) 1. Start the car 2. Let it idle for 2 Minutes 3. After 2 minutes push down the brake pedal and HOLD it 4. While holding the pedal down turn off the car 5. The pedal should NOT rise for at least 30 seconds 6. If it doesn't rise then the Check Valve is good 7. If the pedal rises before 30 seconds then the Check Valve is faulty.

Test 3) 1. Shut off the Engine 2. Pump the brake pedal 4 times 3. On the 4th one keep it pushed down and start the car while holding the pedal down 4. The pedal should sink down. 5. If it sinks, the booster is Fine.

Myself, I'm leaning towards the master cylinder having an internal 'leak' or bypass problem.

Hope this helps.

The only adjustment you have is pedal free play. The rod attached to the end of the clutch peddle has a threaded adjustment and a stop nut to hold it in place. Free play should be about 1/2" measured at the pedal.

There are couple of things I would check out that would cause this problem.

1. The Mass Air Flow Sensor. It measures how much air is going into the engine. Should be located on top of air filter box.

2. The air tube that goes from the Mass Air Flow Sensor to the throttle body. Check for leaks that would bypass air from going through the Mass Air Flow Sensor.

3. The Throttle Position Sensor. Located on the throttle body. This tells the computer what position the butterfly plate is on the throttle body. You control this plate with the gas pedal..

1. Turn the key to “Run,” but don’t start
2. Press “ENG MET” on the Trip
the engine.
Monitor. Then, within five seconds,
press it again.
3. Within five seconds, press and hold
“GAUGES” on the Trip Monitor. The
“CHANGE OIL” light should flash.
4. Hold the “GAUGES” button until the
“CHANGE OIL” light stops flashing
and goes out. This should take about
ten seconds.
When the light goes out, the monitoirs
reset. If the monitor doesn’tr eset, turn the
ignition off, then try again.