So my XJ started overheating. I pulled the thermostat and it warms up to about 180 in about 30 minutes and stays there. When I start down the road it runs up to 225. Plugged radiator or head gasket? No water in oil and no apparent oil in water. No smoke or wet tailpipe.

 

Removing the thermostat is counter productive and can actually lead to overheating at speed. The waterflows freely though the radiator and doesn't have time to dump enough waste heat before going back into the engine.

Typical guidelines when troubleshooting cooling systems

Over heats at idle or very low speeds - air flow issue such as clogged radiator fins, bad fan clutch weak or bad e-fan stuff, missing fan shroud stuff like that.

Overheating at speed is typically caused by a water flow issue. Clogged radiator tubes, bad water pump, stuck thermostat (or no thermostat), or crudded up block or a combination of those issues.

This is of course generalized but should put you in the general area of your problem. There are issues that can cause overheating issues no matter the speed such as a blown headgasket.

 

Downs pretty much covered it. The t-stat is important dude, get a Mopar and un-delete it. While you've got it open it's a great time to flush out the system with a garden hose and get some nice new coolant in there.