I think I read some previous posts about stutter and or error code P0299 Turbo Underboost after Y78 completed. Well my 2020 2500 started to stutter at slow speeds while excelerating between 20 to 30, or so, about two weeks after Y78 completed and yesterday I got the check engine with P0299.
I read on a post from somewhere, that P0299 can come from aftermarket air cleaners, well I thought since I just changed my old air cleaner and went with the cheap Fram I might as well go ahead and change it out with a new Mopar from the dealer "Ouch" Believe it or not I think the stutter is gone and no codes yet.
Going camping soon with the 5th wheel, and will update after the trip.