2003 3.0 Misfiring
 

I have an opportunity to purchase a 2003 A6 3.0 from a young kid at work. He's in college and can't afford to fix his car and is trading it for a more trustworthy vehicle.
Definitely misfiring. He took it to 2 different auto parts stores to have free scans done, both establishments told him he had 5 out of 6 cylinders misfiring. I should mention he had plugs and coils done before these scans.
He then decided to go to an Audi dealer and paid them to inspect and scan. They told him only 2 cylinders were misfiring. They were suggesting he pay 800 to start the teardown to see what's wrong.
He drives this car daily, still runs and drives, just sounds bad. He did mention that the misfiring mostly goes away with driving with just an occasional hiccup. He also stated that he smells fuel in the exhaust.
What is the consensus of possible problems? If the misfires go away while driving I'm not really sure it would be an internal and not sure why Audi would suggest a teardown.
Any thoughts or knowledge of a known issue on an 03 would be greatly appreciated.
Thanks