I bought a stock XJ a while back and have been working to turn it into a trail rig. One thing I is replace the thermostat, fan clutch, water pump, and radiator because it was running too hot. It does fine now, except on the trails.

This picture shows the temp that I usually maintain on the trail, sometimes a little hotter, but never into the red. Is this OK or should I keep working to find ways to run cooler.

this is an inline 6, auto, 1996 model on a 6" lift

 

Looks like that you are running a little hot. The first thing I would do is verify that you gauge is working properly. Get yourself a I.R. temp gun and aim it at your t-stat housing and see what temp you are running at. Also how is your fan shroud looking is it in place and all in one piece? One other thing, Where did you get your t-stat from. I know that for some reason the 4.0 has problems with after market t-stats. The best would be an oem from the dealer set at 195deg.

 

I have checked with IR gun and it is really running this hot. I do feel uncomfortable letting get this hot so I wanted to see what others see on the trail. T-stat came from Orielys, shroud is in good shape and properly secured.

 

If you turn the AC on, which turns the electric fan on, does it cool down?