im planning on switching to vacume soon but hope someone can help me for now. my car has original pm system 23,000 miles with exception of accumulator. everything with brakes is fine until i press pedal 8-10 times then the pedal goes to floor. i checked fluid right after this happens and on side of resivour looks fine the other looks like chocolate. if car sits for a bit all the fluid looks fine until i press brakes a few times. im assuming this is air in fluid on the one side since it clears up but what is causing this? thanks for any help,jeff