today i had an exciting moment on the ohio turnpike doing about 80 in the 2001 2.3 5spd and i looked down to check my speed and i noticed my temp guage was buried and check gage light was on.i quickly slowed down and it stayed buried meanwhile the vent wasnt on and i turned it to vent and the heat on and immediately it went back to normal temp.i would assume this is a temp sensor type deal since no overheating elements occured.can i get some opinions and info please.thanks ahead.

 

For one , 80 MPH puts an added strain on the engine to overcome the wind resistance.Trucks are not designed to be very areodynamic.
Something to check would be a stuck fan clutch,making the engine work that much harder trying to spin it at high RPM.
Take a bright light and place it behind the radiator making sure the fins aren't pluged with dirt , bugs ,and crap.