[06bmw-325i]

So I have a 06 325i stock other than lowering kit wheels and muffler delete. 263k miles 6mt. I’ve been having this problem for ab 5 months(since I purchased) where it studders and surges on hard accel. Starts doing it around 3 - 3500rpms and keeps doing it untill I shift it never stops or gets better. This happens cold or hot never really changes however I can unplug my Maf sensor and the car runs pretty much like new. Doesn’t skip a beat but does have check engine light on of course. At first I thought it was my maf sensor so I bought one from auto zone threw it on there and it didn’t change a bit. Any help or advise would be appreciated thanks..