Have replaced the plugs and leads on my Escort GTI but it still has a slight missfire when at idle and the car seems to quiver yet when I drive off it dissapears? Also it tends to hunt quite a bit and also sometimes when I pull up to traffic lights or a junction the idle sticks at 1500 and dosnt drop for about 30 secs then when I drive it again it feels like its running away with me cos its idling high.. grrrr any ideas cos its driving me up the wall