Fouled plugs on 1990 Johnson 200hp

[Iceboy149]

So I got her out 3 times the past three weekends and you guys were right, my 20' flew with the 200hp old Johnson. But here's the thing, I think I keep fouling plugs. THe first time I got her up to 5200rpms she flew and then I backed it down and then she wouldn't go over 3300rpms in gear but in idle she would go to 5300. Then I put all new plugs in as the old ones did look dirty and fouled, all of them. Again back up to 5100rpms this time but this time for about 30 minutes and then the same thing but limping back to the dock at 4200rpms. But now the brand new plugs all look the same (black but not necessarily fouled). And again out of gear she'll go to 5500rpms. So Since this motor sat face down all winter in the garage could this be the result of carbon/oil/general gunk buildup getting flushed through the system?
I took the cover off the carbs and they they look perfect but right where I think the fuel gets injected above the bowl there's a tiny bit of black gunge buildup.
By the way, all the fuel lines, tank, fuel water seperator, everything is brand new except for the motor itself so I know it's getting clean fuel.

Should I just keep popping plugs in her with some additives?

Can it eventually work itself out? Or should I have someone go through and clean up the carbs. Or will the ethanol fuel just keep cleaning the system til its done?

Thanks again fellas.