I have just purchased from a mate an F reg Bmw 320i tourer. The car has come with 12mths MOT but has not been used much in the last 3-4months. When I started it this morning the engine started ok but was mis-firing whilst driving and it even back-fired a few times. After a short run it eventually cleared and was great after that. Is the problem likley to be just leads or something being damp or worn? HELP!