Here's where it stands:

Swapped out the coolant sensor (two-wire) for a spare. No change.

Unplugged decel-cutoff solenoid. No change.

The truck runs and opens its choke completely, which is better than my '87 ever did years ago before I knew how to spell 'metric," it seems. When it gets warm - dies. However, if I spray it with a little shot of starting fluid, it stays running for a second. If I continue to shoot little shots, it stays running on that shot, and subsequent shots for a second, THEN it will catch and run by itself for about 30 seconds, then die again unless I shoot more starting fluid.

I tried to swap in my ECU from my '86 auto, but one of the plugs is different. Apparently they are year AND transmission specific.

The only thing I have not done is adjust the idle mixture screw, and I'll also say that you cannot keep the engine running with the throttle when it decides to die. It's going to die, no matter what you do.

I'm going to pull the ECU and crack the case to check for the fishy smell and any leaky capacitors. Just for kicks, I'll first bottom out the mixture screw, counting the turns so I can set it back if there's no result, and see if any change there helps. Wouldn't that be nice.

AZRaider, I did ask what adjustments you had to make with your new carb and you just replied that you adjusted the mixture screw. You didn't mention that it wouldn't run or anything until you did that. That's why I asked, so thanks for the additional info so I can look into it. Is it screw-in for more rich or is that more-lean? Haven't ever adjusted that one before.

Again, this thing does run perfectly until it warms up. You can drive it about a block. The choke opens fully. At some point it just dies. and it's hard to restart. I must admit, I never saw this vehicle fully assembled at any point until we put it together. The top end was off of it when we got it and parts were in a box. I followed the vacuum line schematic under the hood for hook-up. Is everything correct? Hellifiknow, ha ha.

AlphaMale, BIG thanks for all the texting support this morning. You have helped me narrow down quite a bit. I appreciate it.

John B.