Have you tried doing a coolant flush?
Or bleeding the system?
As there could be air in the system, causing over heating
a coolant flush would remove all the junk build up in the system, and when it is being rfilled it would be bleed therefore solving that problem too.

Its a quick job , and can even be done your self if you have a hose, and half an hour of ur time.
If you need help let me know I have the dodge durango workshop manual