No, no need for gyneacologists on this thread...

Audi A6 2.0 diesel doing my head in!!!

It's an '07 car, on idle, mostly when cold, the revs go up and down between 1000 and 850 rpm...when it does this you can actually feel the car 'shudder'.
It feels like it's misfiring???

When it's warm the revs settle on 900 rpm and it no longer does this.

It display's no faults, neither does it have faults stored in it's memory...

Other than that it drives and pulls fine???

What could this be?

 

Dunno

Possible DMF maybe ?, They cause a few issues

 

dual mass flywheel sounds like

 

Ok, but what would be wrong with the dmf to cause this issue? And how come it only does it when cold?

I'm assuming replcaing it is very dear?

 

This does not sound like the DMF has failed.

These cars are comonly known to have EGR valve and VGT problems due to not being driven enough. Its possible the turbo wicket gates are a bit sticky when its cold.

You need to stick VAGCOM on it and check the requested against actual values for a whole load of things.

Its also worth trying some Diesel system cleaner and giving it a good hard rag.

JAmes.