SeaDoo Challenger Port engine Won't rev above 4000rpm in water fine on trailer

[Poole]

I have read other post but never found the solution. I have a SeaDoo 97 Challenger that the starboard motor runs great on the trailer revs to 7000+ RPM but when in the water will not go above 4000 RPM making it tough to get boat on a plane. I've read about rectifiers and neutral switches but never found what the solution is. Port engine runs great in the water but will cavitate a bit at 7200rpm trying to get the boat on a plane by itself I think.