My 2004 F150 5.4 supercrew with towing package, with 80,000 miles on it has started to give an issue. So when going up long hill or pass or when engine has to downshift under load the temp gauge which has never went about the middle, suddenly goes to hot and message comes up reduced engine power, although it does not seem like it. I usually pull over let it cool and go on my way but same issue comes up. None of the fluids are low. So last few times it did this I just slowed down and after awhile it all went back to normal and I encreased speed and kept on going. This started last Nov 2017 and did it again last couple weeks when I went on vac. I had only 78,000 on it when started now have 82,000. I am original owner and never an issue always keep maintenance on it. I know nothing about all these new engines etc. A friend put his engine code reader on it when truck was sitting here and it showed nothing. Any ideas or suggestions? If i were to take to Ford think they might know since does not do it reg driving?