Does the 87 190 Dt 2.5 have a rack damper adjustment? My problem is a lope at idle that started recently. And sometimes the engine goes into a fast idle mode with an increased rough idle. about 950-1000 rpms. (the engine is at operating temp)

I've replaced the following:
1. both fuel filters
2. delivery valve seals
3. rebuilt injectors
4. motors mounts about 4 months ago.

I'm also wondering if the mass airflow sensor has anything to do with idle on a diesel. I unpluged it while the car was running and no change was noted.

Any help or suggestions appreciated.