I have the same problem with the same truck!
At idle for 12 mins it over heats with ac on. Kill ac it cools back down or rev to 2500 and it coola back down.
So far
New clutch fan
New thermostat
New waterpump
Checked radiator and around same temp at all points
Checked AC freon and level is where it should be.
My plan is to so e-fan conversion with factory fans and factory pcm stand alone so my pcm can control fans not a relay or switch.
Truck has 6" suspension and 3" body
The fan shroud currently is 3" lower on the radiator but is still installed on truck
My thoughts are the body lift pulled the fan further from the radiator causing the issue.
However neighbor has the same lift set up on a tahoe same fan and shroud and has zero issues!
On other thing truck does not burn oil and i do not lose engine coolant either.
Any ideas?
