Well, I unplugged the ECU for 10 minutes, then plugged it back up and went for a 20-minute drive. Initially, I drove on flat streets in the subdivision. After the first few seconds, it ran fine. Perhaps the occasional hesitation when accelerating from a stopm but OK. Then I left the subdivision, which included going up a hill, then driving down to a stop at the other side. After I stopped, the engine died. I went down the highway about 2 miles, then came back, having a little fun with a Sonata on the way. My Fiero performed admirably. I drove through the subdivision again without issues. I then exited, and drove down that hill. Same result. I returned down that hill a third time, with the same result. I returned a fourth time, and managed to go without the enhine dying, although it certainly tried to die.
It almost seems as if my TCC is causing issues. I just don't know why a hill would trigger such.
Certainly, after 20 minutes, everything should be warm. I went through all the gears.
I should also mention that the temp on my gauge only gets about 1/4 of the way. I suspect this is a gauge or sensor issue.