S8 D3 truly random misfire

[Prefferle]

Hi folks,
A truly useful and informative forum.

I have been plagued by a misfire issue that is truly random. One day it’s cylinder 1 and 9 having misfire counts between 9 and 96 with other eight cylinders on 0. Other times these 1 and 9 cylinder will both be at 0 with other cylinders 4 and 6 having misfires with the others all at 0 - very strange indeed!

I’ve since completed the following:
Replaced coil packs and plugs.
Replaced all connector shells on coil packs
Cleaned earthing connections on cylinder heads for coils.
Replaced MAF connector shells
Unplugged MAF’s with engine idling, resulting in erratic idling as it should be.
Carbon cleaned with walnut shell blasting.
Visual inspected inlet manifold for broken plastic flaps - ok.
VCDS scan resulting misfire codes only for engine.

It shouldn’t be compression as the misfire cylinders can change.

Can anyone advise of any other checks I can run?

Should I power off the battery and unplug ECU connectors and check/clean?
Is there an earth connection that can be corroded or something that can cause this?

Thanks guys,