1994 25 hp suzuki

I had problems with motor starting last year so I decided to go through carbs before putting it in the water this year. Went completely through carbs with very fine brushes, no port or orfice left untouched. There was alot of white powder in the bowl, looked kinda like sugar. Hooked to the hose engine starts and idles like a dream, but when I put it on the lake does not have full power, and is not hitting top end. Ran about 32 mph before, now just hitting 20 mph. Work done thus far: Cleaned carbs, cleaned fuel pump, new plugs. Note; idle screws 1 1/2 turns from seated position, also there is a rubber cap covering the bottom of the main nozzle that does not fit as tight as it might should but would not think this should matter being that it is the fuel supply tube. Any thoughts? Coil pack? What are the chances of it getting out of time? Also looks to have some sort of computer hookup, can you run a diagnostic on this motor?