HELP!!! 85 johnson 115 ignition problem

[Mike McCool]

I have a 1985 johnson 115 that was rebuilt about a year ago. It was running great and all of a sudden it was like it dropped a cylender. I found a bad plug wire so replaced all four ran a compression test that was good. Ran the boat again, it ran fine for about five minutes then suddenly started missing again. I think the power pack may be bad, but not sure. Does anybody know how to check power pack?

[boats.net]

Using a peak reading voltmeter test output voltage of source coils, trigger coils and power pack output to coils to see what is not within specs.