It acts like it is overheating more than incorrect gauge, based on how the gauge moves. I plan to measure the current draw with the fan's and headlights on, I may be exceeding the ampacity of the alternator.
Maybe put a volt meter on your temp gauge and see if it climbs when you turn your lights on.
And if you have an instruments fuse pull it and see if the gauge still climbs.
You may be getting extra voltage from the headlights circuit, or park lights circuit either one, and this could verify the possible causes.
