If your a do it yourselfer, you could have replaced
the filter, Mass flow air sensor, Crankshaft position sensor, plugs, and wires for the price of the tow bill and saved the $2500. you paid them.
You sure you are a do it yourselfer ? I figure this forum has saved me $4000. in professional labor costs. I shouldnt be driving a Mercedes but I am.

One thing I would check for mis ire codes...is for a plugged EGR Tube. I paid $100 for the dealer to scan my ML320..Dealer wanted to replace the EGR for $600ish. I went home and cleaned the EGR tube and it was perfect again. It was totally clogged.

From The State of Highest Unemployment and Economic Real-estate Depression..
Michigan

Realtor
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