Wanted to give everyone here an update. I have cleaned my throttle body + reset procedure a total of 3 times, each time it buys me about 2-3 days where the "Shift to P" error will not happen. So my next logical step is to replace the throttle body. I've ordered that part and it should be here Wednesday. Going to put the new TB in, perform the reset procedure again, and run some Techron through.
The last time I cleaned it / posted about it,
@RamCares reached out. I explained I had taken the truck to the dealer 3 times for this issue and each time they could not replicate. My truck is now out of warranty, and I explained that if I take it a 4th time then it should not be on my dime (since they failed to fix it the prior 3 times). Long story short, she said I would have to pay to have them look at it again. So, not exactly the customer service I was hoping for. This error code is going to get someone killed trying to cross a busy highway or railroad.