The diagnosis is for the air flow potentiometer, I presume. It is part of the airflow meter. The whole part is what you see when you remove the air cleaner. The fuel distributor with the injection lines sits on top of it. The air plate is part of it. The surrounding aluminum funnel and upper containment are the body of it.
It takes an hour or two to do the install but there are a few techniques that can be critical. One must know how to do the base height setting for new fuel distributors when changing the part. The fuel distributor is the first part off. Also the mixture will have to be calibrated. One also should have a good idea what they are changing so that verification can be done on completion. In other words if it doesn't fix it, did it fix the fault that was identified the first time.
Bosch Master, ASE Master, L1
33 years MB technician