The air flow senser is attached to the side of the air flow housing. This housing is beneath the air filter & the fuel distributor is mounted to the top of the housing. On most Mercedes this sensor cannot be replaced by itself, only comes with the housing. When this sensor goes bad most engines will have a very erratic idle(common failure). Because of the intermittant nature of this problem a lot of M.B. techs overlook this problem, not easy to Diagnose & repair.
MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS M.B. TECH