Low idle speed

[iPod]

Hi folks 
Tech heads needed 🔧
My A3 2.0FSI 2004 is idling low 650-700rpm
Now iv scanned it with my vcds and showing no faults or misfires.
Here's what iv done so far since owning the car engine wise.
New Egr (had fault code when I bought it, and after taking it apart had the usual sheared teeth on gear)
Cleaned TB and reset it.
Cat back milltek non res exhaust.
Now it had been running fine until about 10 months now.
I can't find any vac or intake leaks at all.
So now I'm thinking maybe it's the pcv failing/failed.
When I take the oil cap off there is a slight suction and a change in engine note with a slight wobble....is this a sign of a failing pcv or normal?
Many thanks for any input.
Cheers

[Trevor]

I know it sounds silly and really basic but have you tried running a cleaner through the engine/intake recently as the amount of carbon that builds up everywhere (including piston rings which can give you the symptoms you are describing). I have done this on so many cars recently combined with a damn good blast to clear it all through....works a treat every time!

Failing that, a leak down test is something that will find or eliminate a lot of suspsect components / areas.

Let us know what you find

Cheers   Trevor