UPDATE! Read post #10 for my solution.
First time using HPTuners, and everything has been going great, so far. Was able to get my 2003 5.3 L59, using a P59 ECM, all set up to run a 4l80e, dual e-fans, and F-body style A/C request. The only issue I had left, was the over-responsive gas pedal.
The swap is in a '92 Sonoma, and a long throw, non-adjustable pedal was modified quite a bit to fit in the stock location. However, at "70%" pedal position, I was at 100% TPS. Another odd part, is that the pedal position will read all the way to 150%. So, basically half pedal, it's WOT.
Through some digging, I found pepole with the same issue, having luck switching to an '06 OS.
Possibly a noob oversight, I found an '06 calibration, and copied the ETC settings. I knew it was risky, due to the warnings posted in the Editor, which is why I'm not butt-hurt about bricking my ECM. However, my naive self figured it was similar to switching to the '06 OS.
Anyways, I flashed the config, and the throttle was totally unresponsive. I basically figured I ruined it, at that point.
Now, trying to revert to the last working config, I get:
"Request download x7f negative response code"
I haven't been able to get past that, reading or writing. However, it will log just fine in the scanner. I even tried bench flashing it, where it had a steady 13.8v, compared to the 11.3v it had in the truck.
So, all in all, don't do what I did. I have another ecm on it's way, but would still like some insight to fixing the throttle issue. I'm not too keen on the idea of a throttle stop, at such a short pedal stroke.
Thanks for reading.