my car seems to have developed a problem when driving at low revs it the rev counter drops to 0 and there is nothing as if someone has turned the car off then if i press the accelerator seems to stutter then rev again back to normal. this is not happening all the time more when cold. but seems to be getting worse. car is running fine but just seems to be cutting out at low revs has anyone had this problem before or know what it could be?? thanks