Hi, can anyone help please? I have a 2005 A4 Cabrio 1.8T and its been over revving for a few weeks now. As soon as it's up to temp rev's start to creep upwards when in neutral from the usual 800 to 900 to 1200 or 1400. It also seems to rev too high when accelerating (or at least it seems to take a long time for the rev's to come back down once the accelerator is released). I have read it could be a breather valve or may CTS (Coolant Temp sensor). Does anyone have any ideas please on what it might be and how to fix it? Thanks.