Hello, I'm Cam. Please include all the details about your issue so I can accurately advise you. I cannot see your vehicle so please be detailed.
These years of trucks with the electric throttle have a couple of very common issues. First and in my experience most common is the ground wire. THe ground runs from the rear harness behind the top of the engine to the rear of the left cylinder head. It is attached at the same bolt as the ground strap at the firewall. I have always been able to find this by pulling on the black wire and see if it gives. The fault has been a conductor broken in the insulation at the crimp. The second issue is the wiring near the throttle body. The wiring tends to break a few inches from the connector. check these out and see. Another common issue is the wiring near the throttle body itself. There are some wires there that can break inside the insulation and cause this. Check the wiring carefully near the throttle and about 6" back.
After I clear the code, I can drive maybe 10-15 miles and the reduced power will overtake the engine again. Today after replacing the throttle body, it reduced speed every 2-3 miles before I got home. Is there a mechanization/scanner tool to reset the throttle body? If so, what or what else do I do?
Not on these, check the wiring as I suggested.