Hi there!
The problem is well known at license built MB-engines from korea (MB100 Van and Ssang Yong Musso Diesel/Turbo Diesel).
On these the delivery quantity of the IP varies between the individual cylinders, causing the shake in idle. It is not too common on german built OM617. The manufacturer of these engines (Ssang Yong) advises in these cases a lowering of the idle speed to 600rpm! It does really help the shake but boosts the vibration. So if injectors are OK and rack adjustment is made then that's what it is I fear. There are places though that rebuilt pumps.
All the best,
Dokta