'90 T'bird

Please help me. My car is experiencing two problems. It won't idle and the brake pedal is extremely hard. I changed all the brake hardware already. However, the problem came back. One of the mechanics think it is a bad module. They tried hooking up a diagnostic computer, but it wasn't reading anything. They tell me I need an Electrical and an Ignition Wiring Diagram. Can somebody help me please?

Dwwood