I have an 04 Sierra 3500 that smokes at idle, a problem I have been chasing for some time now. In the last two yeas I have installed new turbo, new injectors, fuel filter housing. I do a regular oil change, air filter and fuel filter twice a year regardless how much I drive it and it smokes a lot at idle. But it’s not consistent, sometimes it’s smokes a lot and sometimes it’s just a thin haze. I don’t have a muffler or cat on the truck, not sure if that plays any part in this. Anybody have any thoughts on what’s going on??