S8 D3 truly random misfire

[Prefferle]

Update

So got wrapped at work for a few days so finally test drove the car on a few trips and the following are results:
1. Misfire is not present with engine warming up. When engine temperature is mid scale / normal. The misfires are now:
- 000768 random multiple cylinder misfire detected P0300-008
- 000769 Cylinder 1 P0301-008 Misfire detected.
- 000774 Cylinder 6 P0306-008 Misfire detected.
- 000777 Cylinder 9 P0309-008nMisfire detected.
I also have the MIL back on and the New fault;
004229 - Mixture regulation bank 4, range 1. P1085-004 Lean limit exceeded. MIL on.

I checked VCDS Readyness and the secondary air has not passed.. can this be connected?
this seems odd as replaced both vacuum valves and blower a year ago and this was ok... I’ll have to remove wheel liner and check all pipes intact etc...

Based on the above I’m thinking a possible fuelling issue or vacuum leak (?) or possible dreaded inlet manifold flaps issue. Thinking about looking into fuel trims to hopefully shed some light...

Really odd as the engine has no misfires, running smooth when warming up.....

Any thoughts or guidance would be greatly appreciated.

Thanks