I have a 2004 A6 2.7 Turbo, automatic transmission with about 60,000 miles
on it. Yesterday I drove 15 minutes to a store, everything was fine. When I
restarted the car after about an hour the check engine light was on and the
car runs very rough, rough idle, much vibration when trying to accelerate,
especially when the higher gears.

What should I be looking for?

Thanks,

Don