Have you looked in the service manual under the DTC index ? You will probably get a more definitive answer to your problem with a scan that does more than check generic OBD II codes; There has to be some indication when you get into the saved DTC in the cars memory. The MAF and throttle are controlled by the PCM. and the RCM is in the circuit as well. All need to be checked out. A decent independent Mercedes shop would be a good place to start. Your problem is more than replacing simple parts. Good Luck.