2014 KW T-680 idle problem

What engine? Cummins does NOT recommend to idle more that 3-5min.

 

You need to pull codes and see what your inactive faults are, especially as they pertain to the aftertreatment system. Without that, just trying to guess at the issue amounts to little more than pissing in the wind. It could pertain to the dosing injector, piping for the exhaust, the catalyst face could be getting plugged, one of the various temperature or differential pressure sensors could be haywire, could have to do with the DEF doser, or it could be the SCR... and you want us to just guess at what it is?
If you're willing to crawl under the truck and take a look, it could give some insight... is the DPF outlet cracked? It's a pretty common problem, just below were it gets clamped to the crossover pipe to the DEF doser. Are you seeing dry and crystalized DEF anywhere on the clamps or piping? Stuff like that.

 

Is your high temp exhaust light on? If so you are in the middle of a regen. It takes about 5-10 mins to cool down. I have done that too where 2 consecutive days I have stopped and had it regen when I was done for the day. Seemed like about a 600 mile trip. Hope that's all it is. Good luck