I posted this originally over in the A8 specific area but maybe the engine area of the forum will get a bit more traction.

I've searched high and low and done my due diligence but I can't seem to a straight answer to my issue.

First off, it's my understanding that the 350hp 4.2 fsi 32v engines (RS4 BNS engine, Q7 BAR engine, face-lifted A8 D3 BVJ engine) are not necessarily plagued with the same timing issues that the chain driven 40v motors are (B6/B7 S4). Stop me here if I'm wrong but either these engines were a step forward in durability or there isn't anybody writing about them!

My car is a 2007 with the BVJ engine that just cracked 100k miles. It was well taken care of prior to my ownership and I've owned it now for about 25k miles. When I bought it I went through things top to bottom to track down a few nagging issues in addition to replacing every drop of fluid in every system. Drove it cross country and back without issue.

One thing I've never been able to sort though is a bit of a rough idle. And, more recently, the car will stumble horribly with bank 1 miss-fire codes and intake cam over advance codes. But that is only 1 in 50 times I start the car. Occasionally restarting it will make it go away but more often its cleared up the next morning and the engine runs strong. And never ever a chain rattle! Still a bit of 640-660-680RPM idle hunt but no other issues. Smooth and 26mpg at high highway speeds too. I've replaced all 4 camshaft actuators, camshaft position sensors, and crankshaft position sensor (that one was not easy!!) to rule out any actuation or sensor issues. To no avail.

At quick glance the symptoms point to timing issues of old (Actual camshaft position on bank 1 hunts a bit more when graphed compared to specified) but the inconsistency of any grand issues has me stumped. Could it be an oil pressure issue to bank 1? Even when it's really acting up its very smooth under heavy acceleration but almost wants to stall when stopping at a light. But again, although the stumbling is very dramatic, it's very rare. Enough to reach out the the community though.

Thoughts??