Truck bucks under load

Good morning,

How old are the ignition parts such as plugs?

https://www.2carpros.com/articles/how-to-test-an-ignition-system

I would also do a compression test to be sure there is nothing wrong internally.

https://www.2carpros.com/articles/how-to-test-engine-compression

What are the codes?

Roy

Can you provide the actual codes for this as TPS codes will definitely cause this issue. The transmission uses TPS to determine shift patterns so if that is off then it could cause bucking or jerking while shifting. Also, it could cause bucking without shifting due to it varying the amount of fuel it is adding based on throttle input. This will cause bucking as well.

Let's start with what the actual codes are and we can go from there. Thanks