[Masher]

I've been having rough idle for the past 6 months but recently it has gotten worse and also get misfires WOT.
At first it was just cylinder 6 then it slowly progress to the rest.
Now I have cylinders 2-6 all misfiring!!

Previously it would idle rough until engine warmed up after a min but a couple days ago It popped a CEL for the first time during cold start.

Coils were swapped to no effect & Plugs were changed last year with cheapo bosch plugs from amazon(going to buy bmw ones directly from dealership n see if that does anything..)
I did notice that after I swapped my plugs my idle was slightly off as it was no way near as smooth as my original plugs..


I have a feeling its’ my valve cover gasket/valve cover as I park on an incline in my driveway and my cylinder 3 spark plug hole has quite a bit of oil in it which I suspect has somehow found its way to the plugs in 4,5,6 due to the gravity associated with the incline I park on.
My OFHG was replaced 3 years ago and it was replaced last month again but vcg was never touched so i think its that but my logs may tell a diff story.

I took a log and found that the afr’s seem okay for both banks as it seems to snap back right to 249.5 after I let go of throttle.
However, during cold starts I ran a log and noticed that my bank 2 STFT (Short term fuel trims) was spiking quite a bit.
https://datazap.me/u/masher/log-1530...17-18-23-24-25

2nd gear pull misfire on 2-6 around 4k rpm:
https://datazap.me/u/masher/2nd-gear...og=0&data=3-23

After i ran car hard bank 2 stopped misfiring but STFT are still really far apart
https://datazap.me/u/masher/after-ba...&data=23-24-25

My question is since the bank 2 stft are spiking during cold start is this 100% an injector leaking issue? Or can a valve cover gasket oil leak also causes these spikes in STFT’s.

Deciding whether to swap the injectors first or do the valve cover either way is going to be pricey… new valve cover and new index 12 injector prices are absurd!