I'm no genius on these computer controlled cars..(gimme a 440 with a carburetor and I'll make it sing a song!)....but if it were me.........i'd clear the codes by pulling the battery cable for a few, do a throttle reset, and see how it goes.

I think maybe your MAF has been reading one thing for quite a while....now you're really running some air past it and it got a little confused. The Mercedes software probably needs a little time to "learn" it's new environment.

Maybe even run it for a little while.....as I understand....the CEL, once triggered, can take a few cycles to reset itself.