Cutting out when throttled up

1993 65 hp Johnson

I have been helped greatly from previous posts on this forum concerning an idlying problem I had. It idles great now, but yesterday while out for a sail, it started cutting out when throttled up. It sounds like it is only firing on one cylinder, and then will cut back in momentarily. I managed to get back to dock at only about one tenth of the speed I would normally travel.
I suspect that I have a defective power pak. Can someone tell me how to test it?

Don in New Brunswick

Re: Cutting out when throttled up

Start out by checking spark and compression to make sure both cylinders are firing. Make sure the fuel system is operating properly, no fuel or air leaks.

Re: Cutting out when throttled up

Thanks Daviet for the response.
Compression is 120 psi on all three cylinders. I feel very confident that it is not fuel as all three Carbs have been cleaned and rebuilt. After rebuilding the carbs, it ran beautifully for while.
I tried a spark tester and found that No 3 cylinder had no spark. I removed the power pak and discovered that the ground wire had a nick in the insulation. When i attempted to repair the nick, the wire was corroded badly and I was almost into the pak itself before I could find a solid end of the wire to solder a new piece on to. I suspect that the corrosion has entered the power pak and that may be the source of the problem. Right now I have two questions. 1. Can someone tell me how to test the power pak? 2. I priced a new power pak on line and it was around $300 for the part number stipulated for my motor (5004532 - PPACD3 AL67). There is another available for $89 (CD4 0583110). Can anyone tell me if the CD4-053110 will work?