Interested in the outcome here. Not a turbo expert but when things are hard to diagnose like this, it usually ends up being something dumb....... or something that isnt what it seems at the surface in my experience.
I once helped my neighbor diagnose an ingition problem on his Malibu Surf Boat. We did plugs, wires, you name it. It was throwing injector error codes as well.
Had him take me out on the lake and he said watch this. Every time we hit a wave the engine would cut out. Seemed strange how well it ran and what not otherwise which led me to believe it was electrical. Called up my ole buddy that has worked on all kinds of inboard boats for 30 years.....
He says to me, "shake the ignition key". Well Ill be damned there it was, engine started cutting out at the dock. Things were loose and we had bad ignition contacts behind the dash.
Tightened all that up. Problem solved.