I've been dealing with a motor that won't take WOT for about 4 years and finally solved the problem. Changed plugs, wire, cap, and rotor and fixed it. Guess I should have started there to begin with. Now if I can just solve the warm restart problem. Boat starts cold and runs fine, but when I do a warm restart, it idles extremely rich and won't take throttle for a couple of minutes, then suddenly in an instant it takes off and runs fine. I changed the engine coolant temperature sensor with no improvement. My boat is a '94 and the dealers here in the oklahoma city area do not want to work on a boat this "old".
