Sucky brakes

It'll be a power booster problem if the pedal travels a bit with some force on the brakes ("good enough" for normal slow driving) but when you push the pedal hard to stop quickly it gets rock hard immediately but the brakes still aren't grabbing any harder.

That what you're trying to say? lol

EDIT: Also I agree with 67Dart273 100% a total brake job on these old cars is actually not a whole lot of work and well worth it (for your life lol).