I have a spare new-in-box Bosch Mass Airflow Sensor for Porsche 986 and 996 models.
These sell new for ~$250 on Pelican Parts. Please verify that this part will work in your car.
Porsche P/N: 996-606-123-00/14
Note in the photo the seal has not been broken on the Bosch box.
$200 o.b.o.