No Brakes!!!111

O.K., So I'm driving along and NO BRAKES!!!! 88 cherokee stock brakes. There is a hissing sound like a vacuum leak coming fom the brake pedal area....but
when you push the brakes the hissing stops. Ever since I got the jeep 2 months ago the sound has been there but the brakes worked fine. I have bled them once before and the pedal still went almost to the floor but worked. The fluid is also a dark brown color, I replaced the fluid when I bled the brakes but the color came back. What problem could this be? Master cylinder?

id check the vacume booster the hissing sound sounds like your leaking vaccume the diaphram inside minght be torn or damaged? thats where id start looking

the thing thats sgetting me is that the brakes work most of the time. The booster wouldnt have any affect on the brakes working or not, just on how easy it is to push the pedal, RIGHT?

Wooshing is the booster. Replaced mine - brakes work like new. I would highly recommend a full-on troubleshooting of your brake system starting at the wheels and working your way back through the lines to the master cylinder and booster. It may take some time and cost a little $, but having no stop is worse than having no go (IMHO).