Quoted from TheFamilyArcade:

I could use some advice.
2012 A4 wagon (110k miles) and the check engine light pops up intermittently. It will go away and then come back. This despite two visits to the shop to fix various things that were either "throwing codes" or may have been the reason certain codes were turning up (like running too rich, running too lean...how you get both codes is a head scratcher. Had breather (pcv) valve replaced and also had the carbon build up removed. Dealer thought there could be an issue with fuel injectors, outside garage doubts that, because it's not misfiring on the reg.
Car has occasional symptoms of stalling when coming to a stop or taking a few passes to start the engine, usually when cold. These things might happen once every few days or not. It ran a little rough randomly but that seems to have passed with the recent repairs.
Non dealer garage thinks it's something electrical, because of the intermittent symptoms and light going back out at times. But they not really know yet.
Any wisdom or experiences or wild guesses as to what might be causing this?
Thanks!