I checked the DM pin, HFM pin and ISC pin. ISC indicated three codes: 2, 5, and 11. No other codes were present. While performing this check, I double checked the vaccuum supply hoses. I discovered the vaccuum line on top of the intake manifold not connected. ??? I reconnected and the erratic idle ceased. Do the codes indicated relate to a vaccuum problem? Is there a printed code chart avaiable from MBUSA other than microfiche?
By the way, great article. Thank you for the suggestion.