I've got a 94 JGC Limited 5.2 that has just started overheating last couple of days. I replaced the thermostat bout a week ago because I thought it had been sticking. It seems to want to run between 230-235 down the freeway with the a/c running and overheats in traffic. It has been over 100 degrees outside but still I know it shouldn't be running thus hot. By the way I'm not losing any fluid so I ruled out leaks or blown head gaskets.
The fan seems to have plenty of resistance when I check it, but I only have when it's cold. As far as the radiator cap, I havnt noticed any leaks. It's gotten worse last couple of days as far as running hotter.
My ZJ in the Houston drought heat isn't faring very well...after a few minutes it goes to 190 and slowly climbs past 210 the longer I drive...though its not very hard driving. My cooling system is working fine, the intense heat and highway traffic was probably just too much for the system.
We had the same problem with our 1993 for over a year. Just sitting at a drive through window for a few minutes would cause us to overheat and the AC would blow hot air. We just had the transmission rebuilt (this week) and they also replaced a seeping heater hose, the thermostat (and gasket) and flushed the cooling system and it seems to have resolved the issue (knock on wood)