sat i was out on the river. boat was running fine later on i gave it full throttle and it sounded like the engine was out of the water and it was loud like in neutral. so i shut it off made sure everything was fine. started the boat and it ran fine until i full throttled it and it did the same. engine was locked down. so i used it for six more hrs but i never full throttled it again and it ran fine at 3/4 throttle. anyone have any ideas????n ita a 16 foot jon with a 20 hrp crysler.