I already did a search re: Check Engine Code 170.....

I have a 1996 E320 (W210), production date 2/96 with 135,XXX miles

The car has been driving fine. No misfires or any stalling, etc., maybe the acceleration is a little sluggish for part throttle, but no problems with wide open throttle.

I got a check engine light and my local mechanic has found out it is code 170 and after investigating it, it seems that the car is running a little lean and it is beyond the limits of adaptation.

O2 sensors are about an year old and replaced for preventative maintainance and it passed smog last year.

Replace the mass air sensor with MB remanufactured part hoping that was it.....well after driving for 100 miles or so, the check engine light goes on again and again it is code 170.

There is no vacuum leaks in the engine. Could it be that I got a "bad" reman. mass air sensor?

What else could be wrong? Thanks in advance for any advice.