I don't think a clutch would do anything for you, they're really meant to 'release' the fan when it's not needed, won't change anything at idle unless you can find one that spins faster than the water pump, and you could do similar by changing pulley sizes, which may be part of the problem if there actually is a problem .... also a thermostat sets the
minimum temp for coolant flow, has nothing to do with maximum temp, a 180 would be better for engine life and make no difference for overheating .... make sure, using a good laser thermometer, that the truck is really as hot as it seems, don't depend on the gauge .... if you see you'll have to sit so long it'll heat excessively, shut it off!! I always do that in traffic jams or drive thrus - saves gas too boot
also do NOT overfill the rad - some folks think coolant pushed out indicates overheating, but more commonly it indicates you put too much in, need to leave it a couple inches down to allow for expansion unless you've added an overflow bottle setup
Bill
