My Moomba Mojo 2.5, relatively new boat, begin intermittently losing power after running the boat normally then put in neutral, but when I throttle back up the boat has no torc. I shut the engine off and start it back up and it then it runs normal. Seems to be occur more after running pretty hard, tubing, etc. Had prop and shaft replaced recently and shaft was a bit shorter, but fits, than the manufacture shaft. Not sure if this is related or not. Ideas??