Several questions.. Carb or EFI? My boat is EFI and had a very similar problem. The MAP sensor was bad causing a lean condition when trying to accelerate onto plane. Boat would hesitate, pop back through the intake spit and sputter... but once it got on plane seemed to run OK (down about 200 rpms). Replaced sensor and problem is solved.

I had the same problem once with a 454 Mag. Ran good in driveway, revs hit quick, timing was good. Turned out it was my new spark plugs. I had put in some platinum NGK plugs and for some reason they killed my HP.

thanks for the help everyone boat is fixed turns out the magnet was backwards on the pickup, whitch was masking that plug wire 5 and 7 were mixed matched some how and because they fire next to each other it was tring to do them both boat is back to 80mph awsome just in time for summer to just about be over thanks again for all the help

I have had tons of issues with the MSD pickups..componants are cheap chinese crap !!!! had 4-5 failures in one season of drag racing..finally talked to a decent tech at MSD and finally confessed they are indeed having all kinds of issues with this stuff...asked what the cure was....crank trigger...only sure fire way to cure it he said....now I'm running a engine works pro-billet dist....so far so good...even has the MSD wiring connector !!