when i push on my brake pedal, my pedal goes about half way to the floor before my brakes catch, not only that, if i push hard enough, my brake pedal will go to the floor with no pressure. the pedal makes tht swooshing noise like air is rushing out somewhere. when i pump the brakes, bubbles are coming up through the master cylinder. any ideas? thanks

 

also, it is leaking somewhere, cause it was really low on fluid the last time i checked. get this...Sears Auto Center couldnt find out what was wrong with them...they suggested a new master cylinder...the one they replaced two months ago! ahahaha, thanks.