Loss Of Power Sometimes 1964 500 50Hp

[Kokaneekiller]

I Just got this motor and the first trip out it had a spun prop. After a pain staking 4 hour drive I was able to get my hands on a new prop put it on and I figured since it was a two stroke and they like to fowl plugs I would replace them traded out some champion J8C for some NGK 3510 B6S. I got the boat to the water and I launched it fired right up (no cranking on it!) and putted out for about 5 min. then throttled up and broke a plane was going for about 4 min. and just lost power. It was still running and moving forward just not a full power sounded like it was at a dogged out half throttle. so I turned around and headed back in and was thinking maybe it something obvious so I pulled the cowling and seen that the #2 cylinder plug boot had melted and was falling off I went to pull on it lightly and it pulled the guts out and the motor just seemed hot. so i pushed back on and put everything back together and started the motor (to get back in) sounded like it was running fine I even throttled up a little and it acted like there was nothing wrong. So basically my question what the heck just happened is it something I should be worried about can I just replace the boot and be good or is there something else at fault. I would greatly appreciate some feedback.

Thanks ,
Chris