If I'm doing over 15mph and hit any kind of wave my rpms spike and the moter seems to go into neutral. I have to power down and start over. Is this due to the prop coming out of the water? And if so, should the motor just stay at high rpms with no power in a neutral state until I power down? Like I said it's a mercury optimax 135. I was out on Ontario yesterday, ran excelent at trolling speeds but failed at higher speeds.