Follow up: The new radiator and thermostat seem to have fixed the problem. When i pulled the old radiator off, I noticed that the top outlet, that feeds the thermostat housing, was very weak. I could bend it back and forth quite a bit. There may have been a hairline crack there. If not, I'm sure there were just other weak areas that were causing the radiator to bleed out.
Anyway, after the engine was warmed up, I drove it for about 30 minutes, and the temperature never reached 210. By my guess-timation it stayed right around 195 degrees. So hopefully this is the end of the 3 month overheating saga. The radiator didn't actually start bleeding out until the beginning of this thread. Which was about a month and a half ago. Before that, I could never spot the leak. I just knew I was loosing fluid from somewhere and overheating a bit. I hope this thread helps somebody out if you're in the same boat. I replaced that radiator, thermostat, thermostat housing, and coolant all for around $200.
89 YJ 4.2L Laredo, Howell TBI, Jasper Engine