After telling the "advisor" that I wouldn't take the car back until they had correctly diagnosed the problem (all very calm and professional), the next day he gave it to the shop foreman. The foreman drove the car off and on during the day. When I got there that afternoon, he came to meet with me and said: "Boy, you've got a problem. Needs a new fuel management module." Of course, that was one of the four or five items I left with them as possible causes of the rough running at specific rpm (thanks again, guys!).
So, now they're ordering up all the parts and hopefully they'll fix everything next week.
Although I like the shop foreman, seems to be a "car guy," I remain extremely disappointed with R&H Mercedes in Owings Mills Maryland. Aside from my very first interaction with the dealer, I have had nothing but difficulties with their customer service and unwillingness to take care of business after the sale (For other issues, search under my screen name on this forum).
My AMG purchase in 2.5 yrs will not be from R&H.
Eric M. Isselhardt, Ph.D.
Headmaster, Norbel School
"Educating for a Difference"
Kawasaki ZRX1200 (the faster green one)