When you place it in gear, does the vehicle lunge? Also, is the check engine light staying on while the engine is running? Is the idle smooth when you have it in park?
What I suggest is this. This truck has a can-bus system. CAN stands for controller area network. Basically, all computer/modules are tied together via a few wires. By scanning the entire network, all codes will show regardless of the module involved. I suggesting this simply because it could be related to a few different things which involve different modules such as the TCM (transmission control module).
Here is a video showing how it's done:
If you are unable to get a scanner that can scan the can, see if a parts store will lend you a basic scanner. At least we can check for engine codes.
Let me know what you find or if you have other questions.
Take care and God Bless,
Friday, March 5th, 2021 AT 9:16 PM