OM603 rough idle until throttle blip

[JHZR2]

My 1991 350SD that had a broken cam after my shop replaced the HG is now running beautifully and strong. There are a few things to shake out but I’m happy with how it runs.

But I notice one odd thing, the cold start idle.

When the car has sat a long time, fully cold (which in this weather means an 80F heat soak), I start the engine… glow until the light goes out, crank, it fires and runs on the first cylinder, easily. But it shakes. Not as bad as when it was misfiring with one cylinder inoperable, but it does shake.

Blip the idle and it’s smooth as can be and doesn’t do it again until the next fully cold sit it goes through…

So something is off. I don’t let it idle, shaking like that for long enough to know if it smooths out. I blip the idle and it’s perfect. I wIll note that after the afterglow goes away, and before the engine is full hot, it will slightly show some white smoke. I do need to verify timing.

Any thoughts on what this might mean? A leaking injector perhaps?