I was finally able to track down my wiring issue. I ordered the EVTM from Summit. Thank goodness there's a company that still prints them for these vehicles. I looked on Ebay and its ridiculous what some people are charging for a beat up old used one. The new one was only $40. Anyway...
After tracing the wires on circuit 18 around and lots of testing with a multimeter, I was able to find the issue. The prior owner had installed a
BBK cold air kit. One of those that puts the filter in the passenger's side fender. When they installed it, they pinched the wiring between the fender and the air kit assembly. After enough years of rubbing, it finally cut through the insulation on a few wires and was causing a short to ground on the Red with Green stripe, which feeds into Pin 13 on the CCRM.
The wires themselves were fine, so I put some electrical tape on and I think that will be all that is needed. Now, I just need to figure out how to make sure everything stays where it should when I put the CAI back together.
@AeroCoupe - many thanks for hanging with me and for your advice!
I still have quite a bit to do on the car, but that was a big relief to solve that one. I still haven't actually fired the motor up because I have some other things taken apart that I'm working on. But now when the key is turned the Run position, the fuel pump primes (that was music to my ears), the Check Engine light comes on as it should, along with the other warning lights on the dash. So definitely a victory!