68 mustang

im havng brake problems..at 81,000miles put on new front rotors,calipers pads...rr,caliper...tried to bleed brakes.took 4 ever,,,got all the air out..but pedal goes to floor.took it to a shop,they said ,,i messed up mastercylinder..so put in new one,good 4 a couple days,,pedal still goes to floor...took it another shop,they said power booster was bad,,,put new one in.good for 2 days..pedal goes to floor.put in new check valve.same..took it to a ford dealer,said abs needed to be bleed.....now worse than ever,,,i need help ...........before i changed everything...brakes were fine.never went to floor.when your at a stop sign,and have steady pressire on brake,it is ok.let up on pedal a little,brake goes to floor......

Marc D

Not sure why you felt the need to change calpers at 81K miles but thats not your issue. At some point you introduced a large quantity of air into the system either by letting the reservoir get too low or drained it out of the hoses. The only way you'll fix this issue in my opinion is to have your complete system power bleed. Once air is trapped in all the bends of the truck, manual bleeding will not work. I would take it to a shop that specializes in brakes and alignment and have it done. Good luck