Looking for someone who really knows these engines; first question would be whether the IP is even adjustable for timing on an OM603 or is it electronically controlled?

I am not looking to adjust one, just trying to get to the bottom of a running problem on an acquaintance's car and a supposed diagnosis from a shop out of town. From my memory of owning this model, the IP timing was not adjustable manually like it is on an OM617 or other older MB diesels. Hoping someone can clear this up(?)

Also, what type of problem with that IP would cause a fuel starvation problem that causes a severe lack of power?

TIA. There is a lot more info on forums about the simpler IP on the older models.