[Richard]

So............

Induction leak, or as you have explained your terminology, a CAC leak, would result in a lack of boost. Certainly causing black smoke under load. But the engine would not smoke at idle......

I also think, like George, check the ground supply for the ECM. I saw screen shots of the diagnostics, there was also a low voltage to ECM code.

The coach is in Florida, electrical connections get corroded down here.

I would find the ground point for the ECM and clean it up with DeOxit.