You’ve never said - do you have the Ford factory HD towing package?
Do you think the company that developed the aftermarket “tune” knows more about towing and equipment than Ford does?
Yes, I have the factory HD tow (included with the 202a package). I just made a 5 hour trip without the trailer on the same roads with the cruise set at 80mph and had no fluctuation of engine temps. The truck kept in 6th gear the whole time, outside temps were similiar. It seems when a downshift is needed and the rpms climb on a grade, the engine temp goes up. This is to be expexted, just not as high or as fast as the guage was indicating. I don't believe it to be a flaw isolated to my truck though after reading many similiar stories occurring in the F150s. The popular theory is Ford introduced a pcm update sometime in 2014 to the ecoboost drive train that too eagerly raises the red flag warning of an overheat when towing.