Well, according to Identifix, P1211 (IPR) and P0603 (CPS) are the number 2 & number 3 searches for this year/make/model.
P0122 (Accelerator Pedal Position) is another common code/issue.
Given the programmer, and your report that it's worse with the tuner on Performance, I'd have to say it's the HPOP running out of oil. Canned tunes on chips or programmers are notorious for this. If the truck has a ton of miles on it (over 250,000) it may be a weak HPOP *in addition* to the crappy canned tunes.
I think if I were you, I'd throw that programmer out in the giggleweeds and get a Hydra setup from Power Hungry Performance. I also know a private party that sells them (GaugePro Joe).
You have a chip that you program right off your laptop, you have access to the entire library of tunes (800+) and is a sub-half hour install. (Watch the video on YouTube. It will keep you from making a couple of mistakes that may prove costly)
Your Cam Sensor code makes me nervous, I would change the CPS just to say you did. A 10mm wrench is all that's needed. Right above the main pulley on the right side of the very front of the engine.
The go-pedal code.. well, I think I would clear it and see if it comes back AFTER you do the two above.
Note: you're going to NEED a scan tool for this truck. The $50 ones AutoZone and Advance use will not read manufacturer specific codes. And they have REALLY come down in price (you can get an OTC 3209 from NAPA for under $300.)
Good luck and Welcome!