Yep, you got an intake backfire.
DO NOT , fiddle with the gaspedal while trying to start the engine.
On some engines ( not necessarily yours ), an intake backfire can collapse lifters, and after the engine starts, it will run like crap for a few seconds, before the lifters " pump up " again.
I would suggest you take care of your MAF problem a.s.a.p.

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2007 C 230 Sport.