Hy 46chevinline6, what you are describing is what happens when the master cylinder piston is not allowed to return to it's fully at rest position. There is supposed to be a clearance between the pedal linkage and the master cylinder piston, the brake pedal must be pushed a little before the master cylinder piston moves. One other thing that can cause the problem you describe is a plugged compensating port in the master cylinder, if you remove the cap from the master cylinder and look inside you should see two holes at the bottom of the reservoir one approximately 3/16" and the other very tiny, the tiny hole is the compensating port and it may be plugged with something, hope that helps.
