I just bought a 05 from a dealer auction. They say it shifts hard under light throttle and the factory PRNDL display doesn’t work and it has as screen on the dash for s PRNDL display.

I have no experience with the older trucks but guessing aftermarket tune.

Anyone guess what it may have and how to return to stock as I need it to be 100% stock for my customer.

I know it’s vague but it’s all I was told. I’m hoping I can just get a dealer to reflash the PCM.