PROBLEM FIXED!!
After looking at it briefly, and realizing I just didn't have enough time or knowledge base to mess with it, I took it into the shop and had them deal with it. I have wanted to install some LED taillights anyway so figured this would be the time anyway.
So the problem all along had nothing to do with vacuum pressure, or my tail lights, or my hard hit on Kenny's Climb. But rather it was my trailer wiring. The wires were broken and corroded and were shorting out on the body. I never would have thought of checking that!!
All good now, running fine, and all new LEDs!! Now at least, I have my back-up vehicle for Safari running, hopefully I can get the CJ going now, wish me luck on that too!!
Thanks everybody for you help and suggestions!!!!!