C6 A6 4F 2.4L V6 idling rough

[Ape]

We did basic maintenance for my Audi C6 A6 with the 2.4 liter gasoline V6 engine, changed the oils, oil filter, air filter, spark plugs and camshaft position sensors (the engine light was coming randomly on related to these, fault code P0346, scanned with OBDEleven). At first, everything seemed fine but after a little test drive, we noticed that when the car was idling, there was quite a lot of vibrations. Someone said that after disconnecting the battery (which we did when changing the plugs, which apparently is not necessary :P), the throttle body needs to be aligned. I did the alignment (again, with OBDEleven), and we took the throttle body apart to clean it up and then did the alignment again. Now it was running much better, but still the idle was rough.

I checked the engine live data, and noticed something: misfires happened in the cylinders 4-6 (I assume the driver side cylinders in the V6?) when idling, but as soon as the RPM rise above 1000 (so just a little gas), the misfires stopped. But when the throttle is released, they start happening again and the idle is rough. And also the camshaft sensor fault code came back (P0346, bank 2, again, I assume it's the driver side sensor).

Anyone have any idea what could be the culprit? I of course immediately feared the infamous timing chain (or the tensioner), and checked the camshaft adjustment angles (someone said that they could be used to diagnose the timing chain stretch), and in the bank 2 the adjustment intake angle was ~3-4 degrees:


In the bank 1, it was consistently 0 degrees.

Also checked the MAF-sensor values. ~4 g/s when idling, and ~20g/s when ~3-4k rpm in neutral, which seems to be in line with what it should be?

Really appreciate if someone has any ideas that could help diagnose the issue

[estomax]

What did you gap the spark plugs to? That seems like the most likely source of the bad idle if it wasn't doing it before. Or the coil packs themselves are going bad and its a coincidence through you taking them on and off - you could move coil packs around and see if misfire follows.