I had a break through today. New battery a few days ago. After changing the three port plugs and the #2 plug, which was also dark varnished like #1 (I threw in the towel trying to get the boots off #4 and #6 in very limited space, but hoped they looked as good as #3 and #5)
The boat jumped out of the water in three seconds and reached previous WOT rpm quickly. ...the power is back.
I was on a short time frame verifying any improvement between thunderstorms before loading the boat to the dealer. It was a very short test run. I canceled the appt. We'll be back next week and I'll see if the improvement is here to stay.
Thanks for your advice on the battery and ignition improvements. ...seemed to cure my problem.