I only have a Haynes manual for this car and it totally sucks. It actually isn't even my car, but I'm doing a lot of basic work for a buddy of mine. I replaced all of the vacuum lines on the upper intake fixing the erratic idle. I also cleaned the idle air bypass and throttle body. It was the hoses, they were all cracked, worn, and some weren't attached by Midas when they fixed the leaky coolant bypass on the EGR plate.
Anyway, the tach comes up to 3000 rpm right when you start the car and stays there. At some higher rpm the tach starts to move. It moves from 3000 to
5500 if you drive the car hard. You never really have an indication of what rpm is though. I need to know how the tach gets its information and what sensor are the input for it. A wiring diagram would be super helpful from the Ford shop manuals. I may go to the local Ford dealer and see if I can have a peak at their manual.I've also flushed the coolant, brake fluid, tranny and rear end fluid on this poor car. It runs great, but has had lots of basic maintenance neglect.
AnthonyS