Here's an update on my truck:
The running problem was that I had the #2 and #4 plug wires switched at the distributor. Once I got that straightened out the truck purrs like a kitten and has good power. I fixed a multitude of problems to get to this point.
The ~4A current draw ended up being a bad diode in the alternator. A rebuilt alternator cured that issue. So now I have a truck that runs well and the battery doesn't discharge every week.
I still have a couple of minor issues:
1. the temp gauge doesn't work (sending unit?)
2. the fuel level gauge doesn't work (will use trip meter)
The only thing that still bugs me is that I never made a confirmed connection to the ECM with either my scan tool nor using the jumper wire and flash method. Is it normal for this year/model to not read anything from the ECM if there are no fault codes present?
The truck runs too good for there to be an ECM issue.
The truck is rust free with a straight body and fair interior (needs seat cover). The tires are like new and the battery is just 2 years old. So far I'm into it for $1550 including the purchase price. It had only been driven ~1500 miles since 2004 by the previous owner, my brother-in-law.
Tomorrow its going to the inspection station and then to the tag office for plates and registration. It will be road ready just in time for the next snow