1998 150 hp Oceanrunner - breaks up and surges at idle

[Windstorm]

I've owned this boat about 5 weeks now. only used it about 5 times.
This one seems like a tough one. When I initially run the boat it idles with consistent speed but slightly rough. It will power up fine and run strong and smooth. Never given me a problem while under power.
Then if idled down and run for another 5 to 10 miniutes at idle or restart after sitting 5 to 10 minutes the motor misses, and surges, comes back to rough idle coughs and sometimes dies. It will not rev up with added throttle often dies. Marina can't find the problem yet.

[boats.net]

Sounds like running too lean, carb or carb synchronization problem, air leak in intake or possible a vapor lock problem. May need to clean and sync carbs, check intake gaskets.