Your issue could be one or more of several things, I have seen issues with throttle bodies, fluid, gas pedals and conductor plates with your symptoms. If you have the car scanned by a Mercedes laptop they can prevent you from replacing parts unnecessarily. Are you confident in your fluid type and level?

As for the conductor plates, I will only sell the oem latest revisions. There are many old or aftermarket ones on ebay for much less but there is no way I want to do the job twice in place of using the right part the first time. I've seen the sting happen too many times. As for the other link above, that is below our cost and we get good discounts as I have been dealing with these cars for 20 years now. I can't touch that price for the latest revision, and i'm not interested in selling the old ones from an OE supplier that has old stock they are trying to flush. Sorry i'm not the cheapest, I try to be so when I can and am happy to revisit pricing on anything that doesn't seem right. If it helps I can discount the conductor plate for you by 10%, i will change it now and keep that active for a week for you if you determine that is what you need.