I have the famous BLB engine in my A6, just had it on the computer and had all heater plugs changed this week. No faults showing. When I start the car the idle plays up a bit. It happens between cold and quarter heated this occurs. If I don't let the car heat fully, its prone to cutting out. Starting the car can become quite difficult then. It will eventually start after a while. Anybody any ideas what this may be? The car runs perfectly once its heated.