Surging issue

I have a 2010 Tundra with 5.7 engine that runs like a top until you put it under a load. I pull a two horse trailer a fair amount and going at highway seed I get a surge in power. You can feel the pulsating and see the RPM drop by one or two hundred and then pick up. To continues when accelerating slowly but if you step on it hard it stops surging. Trailer can be empty or loaded same thing. Any idea what it could be?

 

Not sure when it's under a load, but a dirty throttle body will cause surging rpm's.

 

Try to run a couple of cans of Berryman's injector cleaner through a half tank of fuel.

 

Cleaned the throttle body and MAF sensor and that did not cure the surging. I will get some Berryman and try that. Any other suggestions?

 

Do you have a pedal commander installed by chance? If so, I would uninstall / remove it and see if that cures the problem

 

Could it be transmission related? Check the fluid level? Ever drain and fill?