I highly doubt it is the coil pack as a failing coil pack would show consistent symptoms not sporadic. A failing or temperamental crank sensor however will NOT show an EML light. A total failure of the crank sensor will but one that doesn't send a signal from time to time will not and I would go with this rather than the coil pack. Since there are no other issues with driving the car then I would assume crank sensor. Has it had a clutch change recently or done any work to the gearbox?