Hi Sean,

<< Scoped the coils - look OK >>

What did you see on the 3rd coil wire? Part of the Ignition current monitoring circuit is external to the ecu in the form of a resistance between the coil and ground. The third coil wires are linked and go through an inline resistor to the earth ring mounted at the t/stat housing.
I have seen a couple of these open circuit before but as far as I recall this only caused fault codes without any running concerns, as you would expect. Worth checking anyway.