I agree with the previous post. Check the timing chain for stretch. Mine was quite stretched and I replaced it right about the same point (212,000kmi). The valves are hydraulic, so that should not be a problem. I would replace the filters (air and 2 fuel) along with the oil and filter.
It would also be a good time to run some diesel purge through the fuel system. As it is a new car, I would suggest running two cans through the system.
The best manual for this car is the Mercedes CD. There is a Haynes manual (not available in the US, only in the UK) which covers the 2.0 and 2.5 diesels (the US 2.2 is close to the euro 2.0, especially in early 1984). You may be able to purchase it on the internet (I purchased it when visiting Europe along with two german repair manuals for the 201 diesels). The available haynes manuals do not cover the 60x engines and they are quite different than the 61x engines. There is a chiltons 78-84 which touches on the 2.2's, but it is really poor.
I hope this helps; If you would like, please feel free to contact me off list.
jjovanovic@factor-ip.com