Weird stutter in my 128i!

[shivers]

Hi all, first post in here - and first time joining a forum like this!

I got my 13' 128i (automatic) last year, got it with 25k miles and it's been a dream to drive since, definitely jumpstarted an addiction to BMW.

At one point, it developed this weird stutter at around the 2k RPM mark where the car struggles a lot to go up to the next gear automatically, so it hangs out the 1800-1900 RPM mark and when I let go of the gas the stutter stops. If I press on the gas harder, obviously it goes up but it still jitters. If I drive the car on the steptronic transmission, I noticed that this is less likely to happen if I make the gear changes myself, but it still jitters every so often.

I took this to my mechanic, and they suspected it might have been axis related since my back right axis was loose, however even after fixing it, the weird stutter/struggle continues.

Does anyone have any experience dealing with this? I am hoping it is not something serious and I guess I am looking for some peace of mind/direction of where to take this.

Thank you all in advance!