I just ran wires for an amp, and drilled through the firewall. The hole exits just below the plate that the brake setup goes through. I'm not sure if any of this caused the problem I will describe below, just something that I thought might help..

Problem: Start the car (hear a slight hissing sound while the car is running). When I step on the brakes, it is VERY stiff, and I notice that when I step on them while not moving, my RPM's clime to 2000. Also, while moving, the brakes are VERY stiff and do not slow the vehicle down much at all.

Any help is much appreciated! I consider my car not driveable because of this.

 

Quick addition: The RPM's don't go up when I press the brake, but they climb when I start the car in an unusual way. Also, the hissing sound lessens when I press the brakes harder and it goes away when I accelerate faster.

The way the brakes feel is almost the same way it'd feel if you lost power steering, as a comparison.