I have recently changed the airfilter in my S3 as part of a service. I changed the original paper filter like for like. Iafter donig around 500 miles i started to get a misfire and cut out at high revs at high load( 3rd and 4th gear). Sometimes the Traction control light would come on solid and sometimes it wouldn't. Same again with a scan, sometimes id have an intermittent MAF sensor high fault and sometimes i wouldnt. Opened up the air box and found what can only be described as an oily water stain on the top of the airfilter that looks like it has come from the plastic breather pipe, (im not sure what this pipe connects to but it goes down the front of the engine to near the oil filter). The car feels down on power but will drive normally at normal pace. Car is also always ok at full thottle in second gear. This fault usually happens in 4th at full throttle above 4000 revs. Any ideas any one?