I have a 2013 jk unlimited rubicon . I’ve had issues with the temperature creeping up on the gauge . Soo , I replaced the thermostat and all the hoses and had a coolant flush . Seemed ok for awhile then it just started heating up again . So I thought perhaps the radiator was plugged . I had a shop put a new one in and I thought maybe that would fix the issue .Jeep ran warm around 3/4 up the gauge through most of the trip then all of a sudden it spiked up to hot and the dash lit up with all the warning lights . Went into limp mode and threw code P0420. So I figured plugged cats . Well just had them replaced and it’s running at 240f . I don’t know where to go from here. The fan works

 

Just a few thoughts. Could be a sensor especially the oxygen sensor. Are you sure you don't have a head gasket leak or water getting in the oil? Is the the water level dropping at all? Did you make sure the water pump is OK? is the system burped?

 

gotta agree with RonandJanet after everything you have changed out it has got to be something in the engine. Head gasket leak how ever minor will cause this issue. Pull spark plug and check to see if colored white or tan indicating water has entered the cylinder.