I have also fought this problem for at least 2 years. Most of the people in the parts stores cannot understand the concept of the second sending unit for the guage. I finally gave up. My radiator is new, I keep the system flushed/full, and hope for the best. I have wondered if there would be a warning light on the dash that would come on during overheating, though, since that is managed more by the computer. Anyone know this?
1994 YJ, 4.0, auto, only 63K miles, RE 2.5" XD w/ OME shocks, discos, JKS telescoping trackbar, Creager 15X8 soft 8's (4" BS), BFG MT KM 31X10.5X15, SRC Front/Rear bumpers w/ tire carrier