I'm very surpirsed you didn't get some opinion from Brett Wolfe. This problem should be right up the old CAT Club's alley, and should have been resolved by now. My coach spends a lot of down time too, but for financial and logistical reasons, not engine problems. I would think that if it were at Peterson CAT in the Willamette Valley or Redmond, or even at BCS in Bend, someone would have pulled out the stops to ferret out the cause and fix it. But getting it there from Alabama would no doubt be no small feat, given the distance and the issue. It's very puzzling that your sensor exhibits a code that not even CAT is familiar with.
My highly limited input here is to proffer that the throttle position sensor needs recalibrating, but you probably already have been there done that. Whatever's haywire with the TPS system, I wouldn't think it so difficult for a knowledgeable CAT tech to run down; the fault is obviously sending a signal to the engine ECM to revert to low idle. I don't blame you for being tempted to throw a new TPS at it, but would hope someone here or at the CAT forum would offer alternatives - a new TPS may not fix it, and more $ down the tube, but then again it may be just the ticket.
Joel