Gilly- I cannot tell you how long it took me to find this post.
quote: In over 90% of these 2 codes, it's the mass air flow sensor. Other 10% it's a vacuum leak, usually in the induction system after the mass air flow sensor. You could also look for a huge blockage in the filter box, we had one once where mice or squirrels attempted to build a nest in the bottom of the air filter box, which realy plugged the airflow. Ran bad too though and had these codes. Pretty confident it's the mass airflow sensor though.

I bought not one but 2 sensors thinking the 1st was a cheap $90 ebay chineese one. replaced the plugs..paid a pro $90 claiming he found a wrongly routed vacuum line..
then reading your post i sprayed starting fluid around the mass of vacuum lines in the back of my engine near the firewall and heard the RPM's pick up.
It took another 50 minutes with mirror and flashlight to find a gizmo came out of its hole to the intake manifold. Just wanted to thank you. Steve.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles