I've been chasing a rough idle on my 2014 A6 for months, throwing parts at it like spark plugs and coil packs with no luck, and I was about to give up until a colleague told me to visit our car service center that specializes in German engines. They hooked up their diagnostic tool and within ten minutes found a vacuum leak from a cracked PCV hose that every other place had missed, plus they cleaned the throttle body while they were at it. The car idles smooth as silk now and I'm kicking myself for not going there sooner. Anyone else here had a similar issue where a simple vacuum leak caused all sorts of headaches? Feels good to have the old girl running right again without spending a fortune.