Damn, I was hoping there wasn't going to be any "unseen" problems from the electrical current.

I'd just replace the wiring for the EGT gauge. You may want to swap out the gauge with another from a friend to see if it's the gauge, too.

As far as the high idle, test the normal things such as TPS and ISC motor. Heck, you may even want to go ahead and check all the sensors while your at it, just to be sure nothing else will creep up. I'm not sure how an ECU is tested, but you may want to do that as well.