For the stuttering, guys, don't waste your money on fuel injector cleaner from the auto store. Half the crap has an alcohol base and can wear down the inside of the injectors over time, and two, its going to be diluted to the point it wont even do a thing by the time it gets in the injector.
I would check the MAF and have it cleaned. Make sure you have the screen still in it. Also have any of you rotated the maf at all? that can play a factor in it.