***Update*** installed the new thermostat and cap and have the same result. I did notice that the heat is not hot either (since my son never mentioned this) and also the top hose is hot but the lower hose is ice cold... I am thinking the radiator is clogged up? This car does sit a lot since he is in college and only uses it while he is at home. Any help greatly appreciated!

 

http://www.ehow.com/how_7369_burp-cars-cooling.html
Might help! Cheaper than replacing radiator! Worth a try!

 

I'd buy a radiator flush kit and try that flushing it might be all you need

 

I encountered that same problem recently with my Durango. Cost of fixing it after it blew the head gasket, $1,300 and counting. We used infared thermo to check the temp and we had the same problem. We narrowed it down to one of three things before the gasket blew 1) thermostat (even though we replaced it we noticed the new one from autozone did not have the pressure thingy (don't know tech term for it but it looks like a back of an earring) but the one we got from O'reilly's did, 2) radiator needed flushing (buy flushing solution from autoparts store), or 3) we had air in the line. No matter how much we bled it when we'd go back after letting it idle we'd still get more air out of the system. We went ahead and replaced everything but the radiator. Maybe it won't run hot anymore if they ever get it running again.

Good luck and let us know what you find.

Ang