Hey folks, I've got the wagon up and running again, and she's better than ever!

This is super embarrassing, but in my frenzied quadruple-checking of everything, I inadvertently switched the #3 and #4 spark plug wires to the distributor cap. Duh. I believe it happened right after I switched out the ECU, because my battery was dead by that time, and I was fiddling with things while I waited for a jump.

Really, I'm ashamed, but I felt I should admit this due to all the help offered by the nice brickboard fellows, as well as for any future searchers looking for resolution to a similar problem.

I do still believe my ECU was bad, because the fuel pumps didn't turn on when I turned the key, a situation that was remedied by putting in a new (used) one (which was $50 on eBay, with a "lifetime warranty"). This is something I double-verified thanks to Art's suggestion.

But I really want to stress how well the car runs now with the clean throttle body! That was totally worth it. It's so smooth now, I didn't even realize how bad it was before. She's very quiet and the slight stumbling while shifting or idling is completely gone! I also modded the air filter box so that it would always take in cool air, and the temperature gauge read noticeably lower than before. It used to routinely show 50-75%, but today, the needle didn't go above a quarter of the way up. And it's in the 90s today! I drove it for about a half hour, shifting through all the gears to allow the new CPU to "learn."

It was due to all this down time that I cleaned a bunch of stuff in the engine compartment (including hitting every electrical connection and ground with electronic cleaner) so no regrets. Keep those throttles, flame traps and oil traps clean!

Thanks again, folks, and try not to be too hard on me, will you?

--
Wine Red 1989 240 Wagon