A week ago Friday I bought a 2008 A6 S line 4.2. It was a private sale. It has about 124000 on the clock. I drove that night down to New York City without any problems at all. Saturday morning I started the car and it started misfiring BAD! When I called the previous owner he swore up and down that he had no trouble. However he stated then that he had a slight issue when he used the push button start instead of the key. I thought no way in hell is that the case. When I stopped for gas and shut the car off I decided to then start the car with the key. NO PROBLEMS then. CEL was off so I thought maybe bad gas or something like that. On my way back to Maine the CEL started blinking and stayed on steady. Yet the car ran fine and I was averaging 26-27 mpg. I had it scanned at a shop I used to sell tools to and we got 9 codes. Mainly misfires on individual banks, a random cylinder misfire and a bank 2 cam sensor. What I found odd was that the misfire is only felt under 1800 rpm. Anything over that and it runs fine. Originally the shop was thinking a bad ECM but now they're thinking about it being a cam tensioner??? Any ideas, are they on the right track? They mainly do VW,s but are pretty knowledgable on Audis from what Im told. Thanks in advance.