my f350 keeps geting hot

[WestTXf350powerstroker]

hey guys heres the deal i got this 7.3 99 with 256k on it and keeps geting hot when i run about 70 to 75mph when i slow back down to 50 or so cools back down in a few mins. if i part the truck and let it run for hours it will never get hot what ya think this could be ?

[STANGMAN893]

Had that problem on my 97 f250 and it turned out to be my water pump impeller rotted away.

[WestTXf350powerstroker]

water pump is about 1 year old i put it on last year and i just put a new fan clucth about 5mins ago tryed the truck out did same thing do you think maybe my water pump has gone out that fast?