Overheating F-250

I have a 1994 F-250 that we have changed the thermostat, radiator, water pump, cap, hoses, and installed a spring fan. New heads. Hot heat in the heater. Itruns normal at highway speed for around 10 or 12 miles and gets hot. pull up and idle and the temp retracts. Even the block has been blown thru. What could possibly be the problem?

If it has an automatic transmission look at the color of the transmission fluid. If the fluid is black it means the fluid is burnt. This means the transmission is running hot. And since the tranny cooling lines run into the radiator and back out, if the tranny is running hot it can cause the engine to overheat.

Tester

is it overheating oe is it just showing on gage overheating. Could be just the temp sensor needs replaced.