You had the tranny gone through didn't you? Take it back to them and let them tell you what it is. I suspect it may be as simple as a tps sender or such. I know on the diesels when they play that game it generally gos to the sensor for determining throttle position.
My first instinct was throttle position sensor as well, judging how it's always biased to a hard shift. Yes, it's freshly rebuilt. Maybe I'll have them look it over... As much as I spent rebuilding it, it should be shifting pretty seamlessly.
I'll pull the codes for my own curiosity and see if it's still spitting out the TPS code.
I wonder if there are any components between the TPS and the computer, anything that could disrupt the signal and play with the voltage. The TPS is brand new and is behaving the same as the one before it.