2000 cherokee, 4.0, auto. So the jeep will be at 210...... Which is obviously pretty standard, until I turn it off. If it sits for 5-10 minutes, it has heated up to about 230 and runs like crap until the fan cools it off (about a minute and a half). How or why does this happen? Ran stock like this for a few weeks (it was happening then and now I've replaced water pump, thermostat, radiator, coolant, hoses. So why does it heat up after being turned off and run like crap?

 

The coolant is still absorbing heat after you shut the engine off, but it's not circulating and unable to carry the heat to the radiator. It's normal, there is really nothing you can do about it. It cools down when you start the engine because the coolant starts to circulate again. You may have a heat soak problem with the injectors when you restart the hot engine. All of the heat is boiling the fuel in the injectors and fuel rail. There may be a TSB out there to remedy the problem.

 

You just directed me to my problem sir. Thank you very much. I've been troubleshooting this for a year. Thanks you very much.