So with perfect timing the 911 just started misfiring, It did it awhile back on a damp day but has been good for a year or so. I'm thinking coil packs, I'm sure I can hear that click you get with an HT leak. My question is are there any variations in type of coil pack fitted, I can see there are different makes. Any help would be appreciated,particularly as to how difficult it is, I've spannered all my life but am getting to the age when I lack confidence, I have done the water pump and all the road springs on this car.