Stuttering during hard acceleration
 

I've got a 2008 A6 4.2 v8. During hard acceleration the car tends to stutter a bit and threw a check engine code as running lean. Changed the MAF sensor already. From what I understand, it could either be a bad or clogged fuel filter or the fuel injectors going out that is causing the issue. Any thoughts as to what may be causing this issue?

Any codes for the O2 sensors?? Those dictate fuel ratio as well.

maybe one of the coil packs are failing? (My old Navigator did the same thing, changed all the coils and fixed it)

Yes. The code is p0171 bank 1 running lean which is the o2 sensor reading lean exhaust. This is why I think it has something to do with the fuel delivery system somewhere. From what I've read, if it's not the MAF sensor then it is most likely something there. Thoughts?

Upon reading another thread, I think it could be one or more of the coil packs misfiring. Someone else was also having this issue. And they also said that their CEL would flash when it was stuttering hard. Mine does the same thing. Almost everyone on the thread was saying that it's probably the coil packs misfiring.

Could also be the ACTUAL O2 sensor that is failing.