I have a 95 f350 the brake pedal goes to the floor. I have changed the master cylinder , power brake booster and bled the brakes. The problem still exists any suggestions.

 

Check the adjusters on the rear brakes. Very common problem.

 

RABS pump could be bypassing. My F-150 had a spongy pedal and that was the problem.

 

Did you bench bleed the master cylinder? if not that is more than likely your problem Air!

 

I had a similar issue with my '92. New bench bled master, front brakes, lines, rear shoes, adjusted and bled multiple times. Did a rear disc brake swap and it fixed it for the most part. now the pedal is better but still a spongy pedal after pressure bleeding multiple times. Next is a RABS bypass..