When I open the trottle and start planning out the motor suddenly revs up more rpm"s like its coming out of water and I start slowing down,but I am still in forward gear. I then let off on the trottle and then give it gas{trottle}again and I go. Does not happen all the time,tried trimming the motor,just seems like the motor prop is out of water or something is what it sounds like,I have a Raker S.S. prop,could it be a gear in the lower unit maybe.