I can't tell you if it's the mass airflow sensor or not, but I replaced mine, and Fastlane sells them for about $240 or so. Much cheaper than the dealer.
I'm telling you, you should check with Phil at Fastlane before you order any parts from the dealer.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".