97 Grand Cherokee 5.2 overheats at idle

Hi guys, sorry for bringing up an already beaten topic but I'm at a complete loss-

I have 2- 97's with the 5.2L both doing the exact same thing and the exact same maintenance list-

Replaced the water pump, fan, fan clutch, thermostat, rad cap. Coolant is new/clean and has good flow. They both run perfect when driving down the road, but at idle get hot fairly quickly. I also notice the AC start to blow warm air when at idle. I can take off and it cools right back down and temp goes back to normal.

I have owned several other 96/97 Grand Cherokees with the 5.2L and eventually sold them because I got tired of fighting this exact same issue... which leads me to believe this shouldn't be a huge mystery and is fairly common... yet, I can't seem to find a resource that can provide a fix. Anybody stumble across the miracle cure?

Go to Advance or Auto Zone get a loaner pressure tester. Install it on the radiator pump it up to 12 psi. Then start the engine and let it idle. If the pressure gauge pulsates it indicates you have a leaking head gasket.
A partially plugged radiator will cause over heating but you indicate good flow.
Bad fan blades if flexible plastic cause problems. I had one break and I got a metal one at a junk yard. Mine broke and punched a hole in my anti freeze bottle.