Hi. We have a 2004 F150 Lariat. Over the weekend we went to purchase a small travel trailer. We left the house and got down the interstate and the reduced engine power warning came on and the temp gauge pegged out to hot. My husband then realized he had been driving for about 20 miles in D2 at highway speeds. Don't ask me how he didn't realize it. Lol So we pulled over and turned it off for a few minutes and started back up and put it in the right gear. Lol Everything ran fine on the rest of the way there. When we get there and hook up the camper and get about a mile down the road it does the same thing. We get it towed to the mechanic and they can't reproduce it. So I'm guessing him driving it in low gear started this and now it doesn't like being under load with the camper. So any thoughts of what the problem could be. Thank you.

 

There is a program in the vehicle computer that is supposed to limit fuel and disable some cylinders when an overheat condition is sensed. They don't contribute any power , just move air through alternating cyls to help cooling and hopefully prevent any damage.Just how much damage ,if any, will need to be determined. If the power loss has gone away , great.
Sometimes the computer will place the system in "Limp Mode" due to the problem.
Sometimes a forced reset will clear the power problem.
That just erases the adaptive memory from the computer and clears any adaptive memory it may have acquired at the time the problem was present.