My zetec (1.25) is "missfiring", recently changed the plugs and the coil pack as suggested on several websites including this one, ran fine for a couple of days and has started doing it again. Basically its fine at speed but it dips of when accelerateing, i noticed as well that there was Furring on contact 3 of the coil pack when i replaced it, but thought this was just due to the coil pack being knackered. can anyone help as this is really doing my head in