The M102 engine is okay, but not as durable as the various M103 versions. The W201 chassis is very similar to the W124 using many of the same designs for the suspension.
One problem you have is age. Even a late '80's vintage car is now 15 years old. Mileage can be an indicator of wear, but years take just as hard a toll.
And ACC/AC systems are weak on BOTH W201 and W124 cars.
1998 C230 "Black Betty"