Hey ya'll, I just purchased a 2009 A4 and I have a hesitation followed buy a "buck" if I try and accelerate through it when getting off the line. Worse on inclines. Occasionally it will stall. It feels like my 3-series did when the fuel pump was going out. I don't think its tranny as the vehicle shifts smoothly after the initial hiccup. Its throwing a fault for camshaft position sensor. From my research, the vehicle is exhibiting typical symptoms for this type of fault. My question is why didn't the previous owner fix it first? Its not a difficult or expensive repair. Any idea why the sensor may have failed? The car is at the shop today. The mech told me that camshaft position sensors don't fail and the problem is likely more severe...

Sidenote: the car is chipped and R8 coil plugs have been installed. The problem seems worse now since I put the car back in stock mode. Were the mods an attempt by the previous owner to put a band-aid on a bigger issue?