2011 SUPRA 22V Indmar 6.0L Engine Overheating at Low Idle Speed

[keithc]

I am having problems with my 2011 SUPRA 22V Indmar 6.0L Engine "overheating" at idle speed. This seems to occur more after initial startup, and not after it has been running for a while. If I allow the engine to idle for any length of time while the boat is still at its mooring, the VISION dash shows the engine is overheating. If I lift the engine rpm slowly the temperature normalises. The local dealer has replaced what they thought may be a faulty temperature sensor, but still no better. The water pump impeller has also been replaced. I have had this issue from day one basically. Noticed at 10hrs. I know have 81 hours and still have the same problem. ANY IDEAS?