My LJ has a little over 100k miles now. Its always run at 210 exactly no matter what I was doing.
A few weeks ago my temp would be erratic, doesn't matter where you were driving, sometimes it will run hot, sometimes a little cooler.. I figured the thermostat may be sticking. I buy a 192 degree, take it apart, and find the housing was corroded and coming apart. So I bought a new one and replaced the temp sensor while I was at it. Put it all back together and burped the system.. All is good. Runs a little below 210... I drive it out to Moab from Houston tx, it did great. It got up to 210 at times sometimes just a hair over, but I figured it was from all the hills.... Few days after I get back my radiator cracks at the top.. I just got a replacement from Orielly's. now it runs below 210 at all times except 60+ mph. Then it goes over 210 a little bit. Anyone have this issue?
I recently had almost the exact issue you did. One thing I found is that the fan clutch was not operating properly. Even though it felt good and tight, it did not have that tell tale roaring noise when operating properly. I used a Hayden HD from O'Reilly and it really helped. I had to replace the radiator, but the fan clutch definitely helped. Maybe it could be your problem. Good luck!