2000 a6 2.7

It all started when a hose on the front under-body drivers side hose popped off (by the wheel). After the hose was reattached the car ran fine for two days. Had the oil changed and immediately after, as I drove out the car would sputter as it accelerated. I turned around and drove back in to the oil change to smell rotten eggs. we couldn't find anything obviously wrong so I took it to vast. There was code that read "torque limitation exceeded".

I'm not sure what Vast did to get the "torque" code cleared but, it's cleared. They performed some other work and got the car running as well as they could. Vast told me that the Air/Fuel ratios on the drivers & passengers side of the engine are "OFF". The drivers side is "17% less than the passengers side". Currently, the car drives like there's a serious misfire, sputtering away.

(there are no codes, no smoke, and still a sputter)

Any thoughts?