cooling problems

I have a 85 king cab with the Z24 engine. I am having a problem with my cooling system, I noticed the other day in heavy traffic that it ran hot so I suspected the thermosat. Then the next day I noticed that it ran too cold going to work. It was not that cold out. I went to the store to get a thermosat but before I got one I noticed that the fan was barely spinning but the temp was climbing. That leads me to think the fan clutch is bad, but how would that effect the cooling problem in the morning.

the fan clutch going out can be to tught which makes the fan stay on constantly or too loose which would let the fan clutch spin too easily..


change out the water pump