Happy to say that I retrieved my E500 from FMW last evening and the vehicle is back to 100% and the culprit was in fact the Throttle Actuator.
Sad to say that Full Service Mercedes Dealerships are, IMHO of course, out to rip off the Mercedes Owner any time they can. My total bill for Paul Lucier to perform the surgery was $1420 and some change. I was charged $963.20 for the Actuator(Part Number 000-141-94-25), $3.80 for the gasket and 4.5 hours of labor. Add to the above the ridiculous amount of $150.00 in diagnostic charges made by Chambers Motors in Somerville, MA (The tech plugged in his interface into my ASR and read the trouble codes- a 10 minute job at best) and the total amount comes to $1570.00
The Shop here charges $584. for the Throttle Actuator and a couple of bucks more for the gasket. Although I have not performed this specific surgery before, the valve appeared to have only four bolts into the manifold under the filters housing. I do not think it would have taken me anymore than an hour to remove the old valve and gasket and replace with the new one and plug it in to the ASR computer.
MORAL - Fight back! When you have a problem with your Benz, call the dealership and schedule only an oil change(cheapest charge) and DONT TELL THE SERVICE ADVISOR THAT THERE IS ANY OTHER TROUBLE. You will not be in the waiting area more than 10 minutes before the Service Advisor tells you that the tech discoverd a problem when he plugged in his Diagnostic Interface.(HHT) Tell the Service Advisor that you are in a hurry and just do the oil change for now but give me an estimate of both parts and labor to solve the "problem" the tech found. If you are handy with tools, fix it yourself with the help of the repair CD sold here for your vehicle or take it to your local independent Mercedes Tech and you will pay about half of what the Authorized Mercedes Stealership will charge you.