98 Durago over heating while idle, not when driving

Only when it's hot, 100 degree's and over, while driving the truck it cooled fine, when stuck in traffic and at a crawl, engine starts to over heat and I have to turn the AC off to slow down the over heating. Once I'm up and flowing with traffice, temp goes down. Any idea's?

Bad fan clutch

If you have an electric fan. Check the fuse box under the hood it might be blown or you might not have one. This was a quick and cheap fix. I had the same problem...the car over-heated when idling or "crawling" in traffic.

You will hear the fan turn on around 210 degree's. If the fan turns on and you still overheat. THEN I would check/replace the Fan Clutch.