[Paul Workman]

With all those random things popping up, GROUNDING comes to mind for me too. And, the two main ground posts (under the MAP area would be my first place to conduct a routine "R&R" and get it out of the way before further troubleshooting begins.

Before you remove the lugs for wire brushing and coating with dielectric grease, I suggest you gather the wires up with a tie-wrap to prevent them from escaping! Once they are serviced you may have solved your problem. But, if something remains, then you can refer to the electrical section of the FSM and start there. (You DO have a copy of the FSM, yes?)