So nothing controls both the spark and the pump? So both went out independently and simultaneously while it was running?

 

I was reading all this at 2 or 3 am so some of what I was reading maybe a little twisted - Even tho you dug into the aftermarket alarm system and it didn't seem to be tied into much in the last year I have removed two such systems in vehicles that have came into my shop that have had the same type of problems. It might be worth while to remove it all together if you haven't all ready

 

Well, I went through the entire wiring to the alarm and saw that it was not wired for the kill switch circuit. It only was wired into the ignition wire for a power source and that's all. So next, I took out the ignition module under the distributor cap and tested it at Autozone. It came back with full green light. Then I tested the spark module. It was working. So the only thing left it could be was the ECM. It's buried behind the glove box and looks like a safety deposit box at a bank. It's not sealed or weatherproofed, and it appears that 30 years of condensation has not been kind to it. It was shorted out and had no ground.
Rather than buy a new used one and match up numbers and possibly have to have it flashed, I decided it was just time to let the whole thing go away. Towed it to a salvage yard and they gave me $225 for it. Sad to see it go, but I could see it was just going to keep nickel and diming me to death.
It's a total shame that after 30 years and 300,000 miles, the thing that killed it was a damn computer. The engine was still strong and passed emissions fine. The transmission was still good, and all the lights and dash still functioned great. I'd buy another Chevy in a heartbeat.

 

Well it should live on for a bit as transplanted parts - thanks for the follow up .....