2003 dodge durango overheating problems

I have 92000 miles on my 2003 durango. Last August my AC was not working correctly and took it to a shop and they put a turbo clutch fan in and rixed the problem. at the end of March I was driving home from work and a light came on my dash to check my temp guage and when I did it was almost in the red. I pulled over and it cooled down and eventually got it to the shop that night and they replaced my thermostat. My truck has never leaked a bit of coolant or oil or anything. the truck ran good and then in the middle of june went to pick the kids up and pulled out on the road and no too far down the road the check gauge light came on again just like before. I was able to get it home. Left home to the shop and it worked fine. They looked at the next morning and told me they drove and had it running at their place for an hour or two and did not overheat and all the fans were opperating fine. I did forget to tell you before they put my thermostat in they pressure checked, drained and refilled the radiator and there were no leaks. they gave me the truck back and it has been fine except for something again not working well with the AC and Meineke fixed something on and it really did not make a huge diffence. Anyways my wife to the truck on a trip, and drove about 2hours and while driving, same thing the check temp gauge came on and it was overheating. This time they allowed some guy take the radiator cap off and put water in there only to have to much pressure and damage the cap. we had to get it towed to a shop and they just replaced the cap and it worked fine, they could not get it to overheat. my wife used it for the next 3 days with no problem. On her way, an hour and half into the drive, they stop at mcondalds to eat. they get back in let the truck idle a little bit while all the kids got it and the ligth came back on like before. they waited 2o minutes and were able to drive it the rest of the way over and hour away with temperature back to normal. Took it to the same shop again and same answer, they were baffled and without doing a cylinder pressure check or taking the radiator out to see if it clogged or if it was bad thermostat (they said it was not) he really did no know which way to direct me. He suggested to go back to the dealership. Also I have never had white smoke come out my tailpipe or any discoloration in my oil or antifreeze. I change my oil every three thousand miles religiously. Any thoughts or any similar stories I would appreciate it. I need to get about another 2 years or so out of it.