On my 79 F150 my brake petal is staying on the floor and i have to pull it back up Autozone said that it was my mastercylinder so i replaced that and the problem still remains so i replaced all my brake line and put new callipers and cylinders on and yet the pettal still will not return so before i go spend 70 dollars on a brake booster i wanted to know if anybody had any clues on to why it is doing this?

 

Look under the dash on the brake pedal arm near where it goes thru the floor board and see if it has a cam type adjuster on it.You would loosen the large nut then turn the smaller one to adjust pedal up or down.