I have a 1999 GMC Suburban 4x4, 2500 ,454 engine ,108000 miles. The engine runs hot at times. When driving down the road the temp is fine. Under 210. When I come to a stop light, the engine temp climbs to over 210 right away, but not to the red zone. As soon as I accelerate, the temp comes right back down. I have changed the thermostat and radiator. The water pump has also been change a couple of years back. Need help on what to check next. Clutch fan? Temperature sensor? How can I tell if these might need replacing? Any ideas?

Thanks.

This could be a sensor issue as I take it it is not boiling over or overheating for that matter. Check the fluid in the raideator when the engine is cold, make sure it's full and then warm it up to running temp. now check the fluid in the rezavuar and make sure it is to the full mark when hot.
Do you have good heat?
Is this a summer time issue as well as winter?
An electric reading guage will sometimes give a false reading.
There could be other issues there as well but I would check the temp of the fluid with a needel guage and compair readings.
I dont think it is the clutch fan at this point. Is your schroud installed arround the fan?
It didnt get removed when replacing anything and not put back by chance

Pressure test your radiator cap. My '97 454 burb had a cap pressure if 15 lbs. Cap went bad and it was releasing at 8 lbs.......ran hotter when I stopped or in slow traffic.

G.A.S., thank you for the reply. To answer your questions, the engine is not boiling over and the engine is not completely overheating. I have checked the fuild levels when cold and hot. They are fine. I have great heat from the heater. I have not noticed this to happen last summer, as to my guess it was the thermostat or radiator. I did put the fan schroud back in place after changing the radiator. I will try and find a way to check the temperator of the fluid and compare it to the gague.

SASSEE: thank you as well for the input as well. I will put on a new cap and see what happens.