hi, under acceleration my car is stumbling and hesitates up to about 2k. It starts every time straight away and idles nicely but it' feels restricted when accelerating and has cut out on the motorway and not wanted to start again unless I pull the vacuum line that comes out of the little black and white one way valve. With the disconnected the car runs fine but surely this is wrong and I need to solve this problem.
I have scanned with vagcom but it shows no fault codes. Any ideas please.