I kind of have the same problem..mechanic told me that it could be the electrohydraulic
actuator that is giving me a rough idle while stopped in "drive". This does not happen all the time though,mostly when exiting the freeway and coming to a stop. My indie
checked current on the EHA and found it to be low ..I probably need to get a new one or scrounge
one from the yards, luckily this part is shared with many 300 series and 190 2.6 series I believe .. I hope to have a new or used replacement soon, and see how it works .
Lots to learn about these fuel systems ..I will look forward to your next posts to see
what results you get ... Thanks css190e 2.6 180k/daily driver/ "it's always something"