Here's what is going on ,i took the my 06 Dodge Ram (Diesel) to the dealership for this problem,Idoling rough with the air on,when you get on it excessive smoke will cover the vehicle behind you and yet will still tow 12,000 lbs like no tommorow note (six speed) ok whats your answer to my problem?........Toy Hauler

 

Flux Capacitor?


Sorry, couldn't resist...Mine does the same but no smoke, it's annoying, but it isn't showing any other effects so I've let it go.

 

Could be a bad canooter valve... Or muffler bearings are shot...