I have no experience with the 2,2 liter Diesel in the W201, but the 190D 2,0 and 2,5 liter diesels are strong as hell. Along with the W124 200D and 250D, these cars are the last long lasting/low service costs cars that mercedes build...
I used to drive a 1985 190D (2,0 liter) with 600.000km and no problems.
Check the trunk for rust underneath the rear window (they tend to leak) and above/under the taillights (previous collision damage).
Some W201 rusts round the jack support holes after some time as well.
Besides that, these cars are great.
with a minor 600+k