My 3500 is overheating under light loads,Less that 2500 when on freeway or in city. When it is getting hot I must let off or the temps will rise to 215. Radiator looks good, no sluge. Could it be the fan clutch? I have done coolant flush, and checked for air pockets- everything looks fine. Need Help!

 

Very likely. Mine did the same thing the day after I bought it. Luckily the dealer I got it from paid for the repair- I didn't have to fork out $$ or get dirty.