I have a 99 4x4. when coming to a stop, my truck would hop in the rear end so i changed the rotors and brakes and bled the lines. Now my truck kinda of coasts to stop, and i only have a 1/2 to 5/8 of a pedal. this morning it did stop better but the pedal was not any better. I bled the lines about 4 times each and no air. what is goin on ? is it possible i still have air in the lines, ? or what about the power assisst, what are the signs of it goin bad ????