I tow and haul a lot. Recently occasionally I get stuck on hills or even have a hard time accelerating on flat ground after coming to a stop. It’s almost as if the brakes are on. I will be revving the crap out of engine and barely moving. Then there is a thunk almost as if the brakes were lodged and then clunked loose.

Also the trucks overdrive has been kicking in randomly after 2nd I think…. Then it will hit 4th and downshift. Is my transmission failing? It doesn’t always do it. What the heck is going on?

Today it kept happening and finally got stuck at the hill to my house. I let it cool down for 10mins and then it just did its usual thing and drove fine.

 

I might be tempted to change the governor pressure sensor/solenoid as a first step, maybe the output speed sensor as well. See if anything changes.