I recently bought a 2001 A6 2.8 Quattro AWD Automatic. It has 100k miles on it and started out running fine until one day after I filled up the tank.

Starting after about 15mi of driving after filling the tank the car started to lose power. While at speed the car felt as if there was no gas getting to the engine, then it would kick in, it repeated this issue for around 5-10min of driving. From what I could tell if I was coasting the issue did not occur, but only occurred while maintaining speed or accelerating. Also, if I had to stop for a stop light during this 5-10min span the car would shut off. It would then start up again just fine, but continue with the problem.

The first time this happened, I added some fuel injector cleaner and continued on my merry way. No problems occurred for around a month. The EXACT same situation occurred just today, filled up, drove 15mi (along the same route, the car even shut off at the same intersection), continued to occur for 5-10min, then the car started running fine again. I am most likely going to take it into the shop this weekend (time permitting), but I wanted to get some opinions first.

Thoughts?

 

Are you filling up at the same gas station? You may be getting crappy gas if the station tank is not maintained properly or if they sell you cheap gas.
Another possibility is a partially clogged fuel filter. This is a widely neglected maintenance item, and something easy to fix. A clogged filter can also burn the fuel pump, a much more expenseve item...

 

They were two different gas stations. However they are located across the street from each other.

 

if you don't have any faults... i'd go w/ the fuel filter

 

Its either fuel filter or water in the gas tank. Try putting in about 3 dry gas and 1 injector cleaner. If its water this might clear it up depending how much water is in the tank. I once filled up and 3 miles down the road the car just acted like yours. I towed it home and got close 2 gallons of water out of it. Water is heavier than gas so it will seperate and go to the bottom of the tank.