I have been running a couple days now after the Euro Charged tune. The high idle seems to be gone and the car is idling properly. It was a four hour drive back to my house from Wizard Auto in Douglasville, GA. Most of that drive was on long open highways and interstates. I did not want the ECU "learning" to just cruise along, so I have been using the throttle hard for the past day around the house here. The car seems to be running and idling good; I am happy with the set up now and thank Rudy for getting me pointed in the right direction.
Donald at Wizard Automotive expected the high idle with the larger 74 mm TB installed and running with the original stock ECU; after the tune he expected everything to be OK and it does seem to be balanced and running properly. Wizard is a dealer for Euro Charged, so they are completely prepared to make the tune, and are very experienced with the Mercedes cars. I was in and out in 1.5 hours and they charged me $96 for their time; money well spent from my perspective.
I had tried the wireless tune with Euro Charged from my home. They sent me two cables which connect from my laptop to the cars OBD, but something wasn't correct. They never could make a connection to my car. Adam thought there was a problem with my computer, and asked if I could borrow a friends. I didn't like that idea so I made the drive up towards Atlanta to Wizard Auto. Donald thought perhaps the problem was in my "Home XP'" software as he runs a professional system on his computers with all firewalls and security precautions disabled. I just don't know what the hangup was with my computer, but do believe Euro Charged could do a better job as to informing customers as to the process and requirements to make their wireless connections.
My car is now running a Needswings single CAI, the cooler NGK iridium spark plugs and Magnecore 8.5 spark plug wires with the 74 mm TB.