Have you tried bleeding the master cylinder? It's really easy to do by yourself with out having to take out the master cylinder itself. You just need two 1 foot tubes that you could buy at a hardware store (like lowes or home depot) for like a buck each. You take those tubes and put them on the two bleeder screws on your master cylinder. You then route the two tubes back into the filler hole on your master cylinder (the place you pour new brake fluid into). Open both bleeder screws with a 10mm open ended wrench and get back into the car. Pump the brakes. Essentially this is taking the air/fluid out of the master cylinder and dumping it back into the reservoir. The air will just float up and out and the fluid will stay in the reservoir. Pump the brakes like 10 full times close the bleeder screws. Be careful when taking the tubes off since there is still fluid in the hose and can get on your paint. I just put my thumb over one end to prevent the fluid from coming out of the tube. Put the cap back on the reservoir and you're done.