At the lake today it started out grate., during the day I noticed a power falling in and out. It happend twice. Thin later all of the sudden the boat almost would not get on plain engine started missing from just off idle, and couldn't notice it after it finally got on plain it has carb thunderbolt ign. On block fuel pump any ideas thanx

could be water in the fuel,change the fuel filter first,you may have to remove the carb&check in float bowls for water.

I also have a 91 454 /bravo and have changed two fuel filters already this year. Ethanol sucks !!! Also I noticed a slight "starving of fuel" at WOT. I took the flame arrestor off and cleaned it in a parts washer, blew it out and re installed it and all was well. Also make sure your tune up is fresh.
Happy boating and keep us posted......