OK, I did some more reading late into the night. Found two guys on MB forums that insist that P012x codes are the sensor at the pedal.

Now, you are getting a MAF code And a P022x code (which is apparently the throttle body). I find it interesting that BOTH the MAF and TB are throwing codes. I also think back to the two cars I know of that ran rough, both were caused by TB issues.
I know that pedal sensors fail a lot, but I"m thinking that would cause an unresponsive pedal, but why would it cause the engine to run rough? The ECU/MAF/TB are what run the engine's fuel/air mixture, adjusting for load, speed and pedal position.

I tend to lean more and more to MAF and TB for the cause here. Sure wish I was local so we could swap parts between cars, cause that would be the cheaper way to drill down on this one.