I've been trying to figure out the source of this very random issue for a while now, and I finally have logs of it. 

My engine runs very well, except for a few random occasions where everything is way out of wack and the car idles for shit.  This has happened like 5-10 times in the last 6 months and this car is a daily driver. If I clear codes with VCDS, all returns to normal immediately.

When this issue is present, engine runs very lean, o2 sensor voltage is very low, and wideband reports lean as well.  Attached, is the "bad" log, and then the "good" log was taken right after I cleared codes with VCDS.  It's like there's a big vacuum leak that I can fix with VCDS.

Fuel trims are just fine, before and after in this case, but I have seen it affect trims if it's in this state for too long. I am stumped as to what would do this.  Hopefully someone has an idea.

clogged injectors, failing fuel pump, clogged fuel filter?

Here's a couple screen shots of both of these plotted.

Notice how the injection time and rpm are the same, although MAF is a tad higher in this state.  I might attribute the raise in maf signal to the engine running rough.

In the good log you can see the o2 signal oscillating, in the bad it's flat-lined at idle.

I'm just not sure how to interpret this.  The engine runs terribly when this happens, as you can see from the logs.  Is there anything else that I should try to log when this is happening?

Yes from long ago.. but I Just wanted to say from 200-500who maestro I never got 02's working consistently. I swapped 02's obviosly. Wires. everything. They would just be 0 stft&lt Wish I had something useful to add like a solutioon, but all I can say is you weren't going crazy.