01 24v runs hot and cuts out
 

I have had this 01 24v 6spd 4wd dually Dodge for about 8 months now and has been a great truck since that until a few weeks ago. The truck started running hot about 3 weeks ago, the needle sits at about 2/3 and stays. If theirs a trailer behind it it sits at about 3/4+up. It doesn't matter if its sitting idling or running down the freeway at 70, it runs at the same temp. I thought maybe it was my thermostat so I replaced it and absolutely no change. The truck runs awesome until it passes the half way point of the temp gauge, when it gets hotter then that the truck cuts out like its running out of fuel. At first its seldom, the more you drive it the more often it happens. I dropped it off at a local mechanic to have it repaired about 3 weeks ago and he hasn't done anything to it. I'm tired of waiting for it to get repaired, I just want to either fix it or sell it like it sits, I don't care! Any advice you could give me is greatly appreciated!