Chrysler Repair: Brake pedal go to floor on occasion,no fluid loss, brake warning light, chrysler cirrus

Question
I have a 1995 Chrysler Cirrus, LX, V6, ABS. Brake pedal went to floor, stopped car, checked all wheels, no leaks, checked master cylinder and is full. Got back in car and brake worked fine for two weeks, then same thing, brakes were working again. Thought it was master cylinder, changed it, changed all the fluid in the lines, worked fine for one week and then again pedal went to the floor.
There seemed to be a growling sound from under the car. The pedal then was hard but the car still wouldn't brake. I finally used the emergency brake.  Then just like that I had brakes again.  Is it sensors? or what? I've checked everything else I can think of.

Answer
Hi Herman,
Does the brake warning light come on, or the ABS warning light? If not, then perhaps your power booster is past the runout position which can be mistaken for "going to the floor". I would check the vacuum line from the intake manifold to the power brake canister to be sure its fittings are tight at both ends and the hose isn't cracked. I doubt it has anything to do with the ABS without its warning light being 'on'.
Roland