Finally found the spare TBI (with injectors) the other day after losing it in the move. I swapped out the leftside injector and started up the engine today. It starts, but won't run steady state, requiring continual applications of throttle to keep running. The injector pattern looks normal now with the "new" injector, so I'm not suspecting that as the problem at the moment. It seems like the engine just leans out big time when I let off the throttle. I checked for vacuum leaks, but didn't find anything abnormal yet. I have an auxillary O2 sensor in the turbo downpipe, which kept reading lean, but in all honesty I'm not convinced that it ever got hot enough to give an accurate reading (due to the repeated stalls and having to keep restarting the engine). The fuel is almost a year old, but I've had older fuel than that in the '69 and it would run, so I don't think that's the problem. I don't have a fuel pressure gauge on it (and no easy way to install one), so I don't know if the pressure is lower than it should be. I suppose if the MAP sensor took a crap and indicated low MAP (high vacuum) all the time it would lean out the fuel. Maybe I'll hook up my 'scope to the MAP output and see what it looks like.
I hate to grasp for straws, but I suppose I could have lost a calibration bit in the EPROM, and that's screwing up the fuel table, but that seems like a stretch. I haven't checked for any codes yet, as the air was getting pretty bad in the barn from running the engine, and I was kind of tired of messing with it anyway.
Not necessarily looking for answers (although I'd take it), but I guess I just needed to vent my frustrations about the car. It ran great when it went into storage a few years ago (at the start of our move back to the midwest), and now it runs like shit.
Oh well, tomorrow is another day.