I have fixed my own 2002 Jeep Cherokee twice for the overheating issue. Overheating can be caused by a number of different problems, but one of the most notorious problems for the Jeep is the 'radiator fan relay switch'. When the temperature thermostat goes over 210, it tells the relay switch to turn on the radiator fan to cool down the engine. If that relay switch isn't working, the fan never turns on and thus your engine overheats. Here's a simple test to check if this is your overheating problem:
1. Start up your Jeep, open the hood, and let it run to the point where the temperature gauge on your dashboard creeps past 210.
2. Once it goes past 210, go over to the engine and see if the radiator fan kicked on. (the radiator fan is right behind the grill, circular with big plastic blades) If yes, then the relay switch is working. If no, then you probably need to replace the relay switch or the radiator fan motor is bad. But more than likely, it's the notorious relay switch.
3. Turn off the Jeep asap to avoid damaging the engine.
You can purchase a 'radiator fan relay switch' from most Jeep dealerships if they have a service dept. It should be around $75.
(I saved over $700 by not taking my Jeep to an auto shop to fix this) To change out the relay switch, you need to take off the passenger side front headlight. There's a black plastic guard behind the headlight and the relay switch is located under/behind that guard. If your Jeep ever experienced this problem before, you may see a cut-out where someone replaced this part before. If there's no cut-out, you can check out this link to see a picture of where to cut.
Once you switch out the part, you should be golden.