You may be on the right track there. Spark failure is commonly the first sign of ecu cap leakage damage.

I'm a little confused. You say the 22 position in the connector is blank, but that the wire was good? I may have some understanding. Position 9 in the connector is blank, and would be above 21. Most connector nubering on Mitsu's is R-L, in this case 1-12 on the top (connector catch up) row, and 13-24 in the bottom row.

Not responsible for advice not taken...