Nancy Knaus

We have a 2010 42 SKQ 

we had that problem, I think it was part of the egr system.  I took it to Cummins in Jackson, Tn,  they first cleared the codes in the hope that was the problem, it wasn't.  He removed the top part of the egr manifold, it was okay, then went to the bottom, all the ports were blocked with carbon, cleaned them out, new gaskets.  It now has so much power now.

I'm sorry about not know the technical names of these parts.  I just watched the service manager 

We also owned an older Monaco, it's been years ago,  it had no compression in one of the cylinders.  We ended up replacing the motor.

I'm sorry I can't remember, It was under the cover on the dash of our 2010 Dipomat. I'll have to get back to you later, as I'm not home right now.

I think we unplugged everything that was unpluggable 

I unplugged it under the dash cover for a day.  It fixed it self