I have a speedboat (96 Bayliner) with a 4.3 Mer Cruiser Engine. Only been used in fresh water. Recently I took it out and at half to full throttle the engine has been losing power and jerking. It will lag and then build the speed back up. It is worse towing people or turning tight. I tried a few things. Tried putting more fuel in and running it on the advice of a mechanic. Don't know if it is the engine timing or carbarators. Any ideas?
