M62TU Dreaded cyl 7 misfire

[Efiftythree]

G'day,
I've been reading this forum for years. About time I joined.
I have an 03' X5 Sport that I'm the second owner. Purchased at 100,000km's or 60,000 miles, which ever way you want to look at it. I've since put another 60,000km (37,000 miles) on it and haven't had an issue with it until now. In saying that, I've maintained it and serviced it, as you should.

I now have a misfire on the 7th cylinder. Fault code is P1355 (Misfire 7th cyl with fuel cut off)

Started off with the engine light flashing once a day. Then once every few hours, now all the time. Car runs like a dogs breakfast.

Immediate thought was coil. Swapped coils to see if misfire moved. No luck. New spark plugs, injector, fuel filter, valve cover gaskets (which were leaking). Misfire still persists. Cleaned MAF also.
Next checked compression, which was ok.

My next thought would be that the PCV diaphragm is ruptured and have ordered a new one anyway, since the car is about the age they like to go bad however I'd expect this to cause a multiple cyl misfire.

I guess I'm writing this post to see if anyone has had experienced an isolated misfire due to the PCV CCV being stuffed.

I live on a farm, pretty far from any mechanic that would have BMW experience and I work on engines (mainly diesel though) on a weekly basis so I have confidence I can sort it but am running out of places to look. I'll check power to the coil and injector but I'm sure they are getting power as It will run on all 8 cylinders when up in rev's, on the road but will still miss repeatedly. Will check voltage though, when I have a second person to give me a hand.

Crank angle sensor? O2 sensors? I doubt they are the culprit as the misfire is isolated to cyl 7. I could be completely wrong though.

Anyone who's had similar issues, please enlighten me with the outcome.

Cheers!

Jono.