Ok,
Got the Mass Air Flow Sensor from Fastlane (mercedesshop - THANKS PHIL!!- The dealer wanted $500 and I got it from him for $300) and in 5 minutes swapped out the old one.

The car is PERFECT.

The whole problem was due to the MAF sensor.

The fault code indicated 02 sensor, but as it turns out a bad enough MAF sensor will set an error code indicating 02 sensor problem as well.

Thanks everyone.