Hey My last problem of the 'sudden shudder & loss of power' seems to have got a lot better since i added a bottle of Fuel Injector cleaner to a full tank, however much to my dissapointment, after i thought the problem had been cured my audi did it again yesterday ( i am begining to suspect it happens mostly when car is cold), after much reading on the web i am thinking maybe the injectors need to be taken out & cleaned. Can I do this?? if so does anyone know of a site displaying instructions/photo's on how to do this? Or is it best left to a mechanic? is it a big job? Cheers! p.s do audi main dealers use Filtron parts in their servicing??