Motor mounts and Injector seals took care of 80% of the rough idle the car had when I first got it, and a spark plug connector took out another 10%. The last 10% could be lots of different things I haven't bothered chasing down yet, as the mileage, performance, and acceleration are all within specs! I replaced the OVP with a new one, mostly to have a spare, but it didn't do anyrhing to the very slightly rough idle as far as I can tell. Hope this helps.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E