I had the identical symptoms and codes on my wife's '98 C-class. To save a few dollars, I replaced the Mass Air Sensor with a rebuild and the car ran worse than ever! It ultimately turned out to indeed be a bad Mass Air Sensor - BOTH the original one and the rebuilt one! I took the loss and bought a factory-new one from the dealer, and it has been perfect ever-since! By-the-way, be sure to change the air-filter regularly to prolong MAS life!