Losing power going up hills after installing new accelerator pedal sensor, then having it programmed. What's going on?

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I spent last spring working on my grandkids 2008 GP, and in trying to clear some codes, I installed a new gas pedal/sensor. The main problem ended up being it needed it's transmission rebuilt, and it took all summer to get that done. (Busy transmission shop). It's now running well and is back in the hands of my grandson, who texted me this evening and told me the car is running fine most of the time, but it's losing power going up hills. I scanned it and got 4 codes that all relate to the accelerator sensor. I paid a shop to come out and program the sensor after I had it in. Is it possible that something that was done while rebuilding the tranny might have erased the pedal sensor programming? He's in college and will be coming over tomorrow after classes so I can put the scanner on it again. He let me scan it today because an issue that it was having last spring was the 'reduced engine speed' (limp mode) message was showing up on the screen, although it didn't go into limp mode. I was hoping this was caused by the transmission problems, but it's still coming on, but not reducing the engine power. But it's losing power going uphill now. I meant to write down the codes but forgot to, so he's coming over after classes tomorrow and I'm going to take it to the shop that programmed it to see what they say. If anyone has had this problem, let me know what you found. Any and all comments, suggestions or ideas would be welcomed. Lee