had a similar problem bogging down on a 50hp, and stalling out, turned out to be the thermostat, it was sticking and overheating the computer then limits the revs to prevent real damage.
launched from Forans round 8:30 am flatlined to 50 point and back in about 30 ft had a nice hit near the mouth of 40 mile but didnt get a good hook and lost it after 10 sec and a few good head shakes as well. loaded up around 2 pm or so.