overheating problem on 1995 GMC Jimmy

what would cause my 1995 jimmy to overheat and cool down while im driving it down the road or if its just running? i just replaced the waterpump and themostat and it still keeps doing it. It is not the clutch fan either. I hooked a scanner up to it while it was running and the coolant temp on scanner was way cooler of a reading then the reading i was getting on temp gauge in the vehicle.I replaced the temp sending unit too.

Asked by for the 1995 GMC Jimmy
1 answer
I would consider getting a replacement gage. Some times it it is better to install an aftermarket gage they can be more accurete than factory. there are a number neat options on the market. good luck
gmd