2012 ISX 12 CM2250 - rough under throttle

[Alan50gt]

Its not triggering any faults. Most of it happening before Nox sensors are up to operating temps im guessing. The problem reconciles itself after the truck runs awhile.

Im currently into the top end. After rechecking some auxilary systems, Monday morning this thing started up after a long cold soak and ran like a complete dog.

Pulled the turndown pipe behind the doser and did some snap tests along with some high idle tests. Not saying the aftertreatment is perfect, but the base issue has to be up front. No excessive soot or black smoke comimg out. When it stumbles and misses, the engine is pumping out a ton of medium gray smoke. (Burns my eyes as it finds its way into the cab) If it doesnt stumble in the range I put it through, it will put out a little puff of the same color smoke when it comes down to idle.

Tried to recheck injector leak when somewhat cold (100 -125 degree coolant temps) but it runs like crap, nearly stalls, knocking, shuddering, surging, all you can imagine. Seems to start in the 17k - 20k psi range when High Pressure Fuel Test is running. Itll get to the 29k limit, but it get real sketchy there for a bit.

Tried blocking off injectors individually and in pairs. No improvement anywhere.

Pulled the cover. Jake and overhead seem ok, I will run it all when I put it back together. Pulled it all to take a good look at everything. Nothing obvious yet. Pulled the injectors. Some carbon on the tips but not too bad. O rings good. Cups look clean and straight. No staining. No coolant loss. No contamination. Cylinders look clean, only fuel in the dish from pulling injectors. (All 6 Injectors replaced ~200k miles ago when 4 of them were on their way out)

Only high pressure test I hadnt run was pump performance, as we did not have the proper fitting for the rail. We're trying to find someone local to test the injectors at a reasonable cost. Sometimes they want 2/3 the price of a new one... but theyre upwards of $900 a piece now. If this all checks out I suppose Ill look into the pump. Sometimes its tough enough with faults, a real nightmare without any.

Thanks for the insite (Pun Intended)