Brake Problems

Hi, I have a 1989 Cougar with non-ABS brake system. The brake pedal goes to the floor when I first press on it , but after pumping the pedal 4-5 times the pedal comes up and the brakes work fine. Ive replaced the brakes, replaced the master cylinder and bled the system and I am still having the same problem. Also, when I first press down on the brake pedal I can hear a big puff of air that comes from under the dash, and after I pump up the pedal I can hear a slight hissing sound while holding down the pedal. Can the power booster be causing the problems Ive been having even though the pedal moves nice and easy once the car has been started? Does anyone have any other ideas that may be causing my problem? Thanks for any suggestions.

Still sounds like you have air in the system. When I replaced cylinders on mine I used the gravity bleed technique and worked out fine. Are you losing any brake fluid?