I have a 2000 Jeep Cherokee Sport with a 4.0 engine (not 4WD) the engine is new (replaced a year ago), and the radiator is new. It has 130000 miles on odometer, but about 9000 on the new motor. The temp gauge will get up to running temp and then it will move all the way down like to to where it is normally at when we first start it up in the morning. It will stay below the 100 mark for a while then it tries to come up to just below 210 and then it goes back down and it might stay there for a 5 minutes and then go back up. Any ideas on what could be wrong. Let me know if you need for info.