Vince and I were texting, but I’ll
post here so everyone can see my thought process. I agree that the resting TPS value is too high, and I agree with the .5V spec. My only objection is that your Joe Blow TPS from O’Reilly, even a decent one, doesn’t sit at that voltage. Maybe a Delco would, and you can add that to the list of OEM replacement parts that you shouldn’t skimp on. The best I’ve ever been able to get out of a aftermarket sensor is .59V after hogging out the holes, twisting it in the correct direction, and bolting it down. I’d try it. It almost sounds like an intermittently failing coil but not enough that I’d recommend a new one.
As far as the TBI goes as a system, in my experience, it can take a ridiculously long time to diagnose issues. My most effective recourse besides working with a rats nest of diagnostic equipment has been to power through the issue till it breaks completely. Once you work the bugs out, though, it’s great. I’ve been driving the bejeezus out of my Jimmy lately. It’s honestly my best vehicle right now. I could hop in it and drive to Commiefornia and back no problem. Of course, they’d probably stop me at Needles and not let me enter because it’s not even federal emissions compliant. Oh, well. It’s not like I want to go there anyway.