hello everyone im new to here and new to audi ive just bought an audi a6 2.5 tdi quattro sport on an 02 plate and it is the dogs i dont know wether im expecting to much but sometimes it feels a little flat if that makes sense for instance in 1st it will quickly get up to 20mph but then its really screaming for agear change it pulls really well in 3rd most of the time but other times its almost as if its struggling a bit ???is this normal ???????any advice would be appreciated thanks.