1990 Chevy 1500 w/cooling system problems

I have a 1990 Chevy 1500, 350 2WD. I cannot get truck to stop overheating. I have replaced the intake manifold gaskets, collant temp sensor and connector (broke it while removing from sensor), thermostat and the radiator cap . I have flow of coolant in the radiator and I even took off the waterpump and the bearings and fins seem to be fine. I am leaning toward the radiator being partially clogged or the fan cluch going out. Which or what do you all recommend trying next?? Also, when I took the fan cluch off in removing the waterpump I noticed some considerable resistance in spinning the cluch, is this normal or reason to replace?? Please help, I cannot afford to continue replacing parts with no luck. Thanks

Does it hold pressure? Does it experience coolant loss?

Does not lose coolant other than the first time it overheated, but that was boiling over from the reserve tank… I had a friend come over with a gauge he put where the spark plugs go and he said everything was fine there, if that was what you were refering to.