Hello all

On another popular topic, on my 2005 X350 Vanden Plas I was getting check engine light and 'Restricted Performance' with the cylinder bank 1 and 2 both too lean. Symptoms were misfire at cold start at idle, pinging (detonation) under load, reduced performance overall accelerating or going uphill. New Mass Airflow Sensor and Air Filter did the trick. Car has full power (been a while) and no CEL or Restricted Performance no matter how hard I push her.

From the boards here I figured it was a vacuum leak or the MAS.

I bought a name brand MAS for $75.79 on Amazon (Delphi AF10135).

Thanks - hope this helps others.