Feels like rear end in bouncing or shutter when braking only thru 25 to 20 mph do not feel anything in the brake pedal. only for that 5mph. 2004 Dodge ram 4x4 short wheel base

Bleed both sides of the rear brake circuit. My opinion is if you're replacing one side of the brakes, they should both be done as both have been in service for the same amount of time. If the brake pedal wants to bounce back at you and/or feels spongy, it's an indication that air is still present in the system. I would completely change the brake fluid in the system (siphon the old fluid out of the reservoir before filling and bleeding to save time). Check the handbrake adjustment as well.

usually if you cant feel a brake pulsation in the peddel or steering, its the rear brakes that may be out of true (warped) if disk. Also bad shocks will no longer dampen braking in rear.

bent rim or hub can cause this. rotate tire to confirm rim are ok and check run out on hub to confirm the hub are ok.

There are 2 ways. It has rear drum in hat style brakes, meaning it has pads and rotors for basic brakes, but incorporated in the rotor is a drum with park brake shoes inside. Remove rear pads and rotors, check the condition of the park brake shoes. Tighten the star wheel adjuster while installing the rotor, keep repeating until rotor feels snug pushing on. Repeat other side reassemble. If still doesn't feel tight, there is an adjustment nut on the left rear side on the cable. The nut is where the 2 rear cables meet, it can be tightened. Do not tighten first, if you ever need park brake shoes later they will not allow the rotors to go back on.

bleeding the brakes -
look fo the bleeder ( zerk fitting ) on the side of the caliper, attach a 1/4 inch clear hose to this fitting and run hose into a catch pan or bottle,, make sure you have plenty of brake fluid in the reservoir ( re-fill as needed during the bleeding process ), have a helper sit in the car and ready to press down the brake pedal, with brake pedal up - open the zerk fitting using a small wrench, have the helper press down and hold the brake pedal to the floor, with the pedal down - close the zerk fitting, your helper can now release the pedal, ( repeat this about 3 to 4 times or until clean and bubble free fluid flows through the clear hose ) --- top off the reservoir with fluid and repeat these steps for the other brake calipers. Note: if brake pedal feels sloppy ( not firm ) then there is still air in one of the lines,, continue bleeding until pedal feels like it has some resistance.

c...

you may need to replace the master cylinder

Did your lift kit come with new extended brake lines?
You mentioned the brakes feel like they are "on" and you can't pump up your pedal anymore.That makes me think that like most lift kits,nothing is provided to re-locate the rear rubber brake line that is mounted to the top of the rear differential. It may be stretched so far that it's kinked on both ends allowing fluid to the rear brakes thru hydraulic pressure but not being allowed to release on it's own. Just a thought. Good Luck!

Sounds like the rear EMERGENCY brakes are binding or your ABS is kicking in.

The E brakes are inside the hub of the rear rotors. You have to separate the rear rotor from the axle hub as the E brakes work like drum brakes. The debris will set off the ABS and bind the rear wheels. Many brake shops and dealers just look at the calipers and pads and do not inspect the E brake.

What happens is if you have a bad front wheel bearing when you brake that wheel will turn in or out,when this happens it throws the four wheel alignment out and since this is a solid rear axle,it's forcing it to flex on the suspension,wich could cause the rear tires to bite on the outside edge of one tire and the inside edge of the other,thats one possible the other would be that the rear brakes are are not slowing the wheels evenly causing the same issue.I saw this problem with a bad front wheel bearing on a Nissan Pathfinder but not as pronouced due to the independent rear suspension. Check the front wheel bearings,which of course will mean getting the calipers off the rotors,and then check for any movement in the rotor,if there is check the hub nut,if it's loose tighten it and check for play in the rotor if there is still play that's going to be caused by a bad bearing.You can check the braking in the rear with a simple spring scale(like the ones used for fishing),with the wheels removed have someone apply enough pedal pressure to just engage the brakes but still allow movement attach the scale hook to a wheel stud and pull until it starts to move and note how many pounds of pressure it takes to move the hub.If it's uneven chech your adjusters and even them if needed and then retest,if still uneven you'll need to bleed them again.As far as the dark black substance in the fluid I would say you may gotten a contaminent in the fluid.Brake fluid gets kind of a rusty reddish residue when it breaks down.If I missed anything or you need clarification don't hesitate to ask I'm home all day.Hope this helps solve your problem.