Motorraum: VANOS noise fixed.......but another problem.

[Glacier]

I think you mean 'synchronized' cylinders.

No INPA laptop I'm afraid. Surely BMW DIS would have found something like incorrect timing in the cylinders?

The coils were OEM BMW.

Yes the 'before' cat sensors are important as you say but, I think there would be a fault code if one was broken.

New valve cover gaskets went on.

Again, if the MAF was suspect I would expect a fault code.

But there aren't any : No

Thanks for your input.