Hello,
I have porsche 2012 3.6L 220kw and I've been fixing it a lot.

I have no error codes, no CEL, just fluctuating RPM's at idle (+-70rpms). I can hear that the engine is not working evenly, it seems like something is not in 6seconds interval. What should I check next?

What I already tried:
1. Changed all coils and plugs - nothing
2. Changed all injectors (to new ones). Event the rail and high pressure sensor - nothing
3. Changed oil mist seperator - nothing
4. Checked if there is vacuum leak sound - nope. (had such issue, the whistling was pretty high and RPMs were fluctuating massively)
5. Removed and smashed catalytic converter insides (there are still a little bit of it left there) - fixed other issue that I had posted in this forum, but idle still fluctuates
6. Cleaned intake valves (there are still some carbon deposits left on the walls, maybe that is still the issue?)

I have a lot of spare parts from other engine, so I'm trying anything I can. Any other ideas? What about vibration damper, is it worth a shot?