I don't know much about ecu's. could it be a wiring fault? or a faulty new coil pack, years back i had a 2.0 wide mouth frog scorpio, it was missing so replaced the coil pack still the same, after much head scratching took the coil pack back and swapped it for another and it was fine, I was unsure if the new coil pack was faulty so ford swapped it just to see and it was..