W124 E300 OM606.910 Cold Miss and Stumble Issue (I've Searched!)

[valvecovergasket]

Ive done quite a bit of searching in hopes of avoiding posting lengthy redundant topics, but cant seem to find anything that mentions this particular issue and before I drop it off at our local Mercedes shop I'd like to at least take a crack at solving it myself.

So far I think Ive read all the W124/OM606 stumble or miss threads.
Seems like most circle back to massive air bubbles from leaking plastic fuel lines, rear cylinder valve recession, failed return line check valves, timing chain issues, etc.
But none of the symptoms really match mine as it seems most have more issues or get worse once the engine is warm.



So... here's what Ive got:

Working with a '95 E300D with 265k miles.
Ive been maintaining this thing fastidiously for the last ~100k miles, have had it roughly 10 years.
Ive done new plastic fuel lines, new injector soft lines (replaced these several times during my ownership), fuel filters done on time, glow plugs have been replaced and work well.
EGR has been blocked off for roughly 50k of those miles and the intake manifold looked good when I pulled it, and I verified the operation of the resonance valve actuators. All looks well there.
I dont have any reason to believe the injectors have been removed as I havent done them, so I'll assume these are original.

The issue Im having seems to have cropped up just within the last month or so as overnight temperatures have dropped into the 30s/40s here in the PNW.

Itll start instantly after the glow plug cycle. Idles beautifully without missing a beat and could do that all day.
However, if the outside temp is below 40 or 50 and the car has been sitting overnight, if it's reved up following that cold start itll miss pretty badly and smoke a bit (blueish/whiteish smoke) if rpms >1000rpm.
Its a miss and down on power that feels a lot like air in the lines or partially gelled fuel.

You can drive through it by flooring it and it gets down the road sort of ok, but still feels like its running on 3 or 4 cylinders and definitely continues to smoke. Part throttle driving during this condition is basically a no-go unless its a crawl in heavy traffic, as maintaining 25mph is tough.
After about 2-3 minutes of driving it clears up and will run perfectly the rest of the day.
You can restart it several times during the day and not run into this issue (ie after 8-9 hours of sitting outside after work, no problems).
It seems to be only after a cold start with a full overnight soak.
Mpgs continue to be in the mid/low 30s and my oil sample reports are coming back really clean with no signs of excess fuel in the oil.

Ive checked for bubbles in the lines during this miss and I see half a second or so of a small bubble here or there immediately following the start, but other than that no sign of any air in the lines by the filter head, even while its missing.

As an aside - I typically run PowerService white bottle diesel treatment during the fall and winter to avoid gelling.


Any ideas of what to check or tests to run?
Im suspicious of the injectors or something to do with the injection equipment, due to the lack of bubbles and the general age of things... is there a cold advance in the pump that could be shot, or a sensor that drives that which could be bad?

Apologies for the novel! Wanted to get all the relevant info down