Almost 1 yr later they think they finally found the issue (my quick test showed positive results). Also apparently between the rad and the AC condenser was also packed. I've always been pretty good about hosing it off to the point where the water flows clean... however I've always been washing it from the front. It looks like I need to re-adjust how I'm cleaning it after playing in the mud (which while I do, if the trail I'm on has it, I'm not a big fan of).
This is the backside of my rad, and they could only tell when I went in complaining that my whole jeep vibrates when the fan is on high. They replaced a module under warranty and washed it all out while it was apart. My initial test up 2mile hill in town here were good... but need to do one where I can actually test it under normal load, and not when I'm just pushing the engine.