Where do I find parts for a 1990 Corolla Coupe?

try your local junkyards.

www.car-part.com is where I go for all the hard-to-find body parts, lights, etc.

yeah, try to find some from your local business netowork, or yellowpage

rockauto.com and (oddly enough) amazon.com are both good options to check out.

Does anyone know where I could get a picture of the colors of wires that go to the ecu-1 in the engine bay I let a friend do some electrical work and now I regret it