I’ve got a 2012 6.7 fully deleted with an air dog that has a bad surge at idle and under throttle. It doesn’t smoke or throw any codes. I’ve changed all fuel filters recently and the fuel was clean. It’s been at my mechanics for a month now and he can’t figure out what’s wrong either. He change outs parts on the air dog then the truck wouldn’t start at all so he put a new air dog on and the same problem with the surge is still happening.