Engine won't Rev after 20 minutes of use when it cold work nice

[Seascorpion]

Hi i have 2008 40 hp 2cylinder 2stroke model xwtl 66tk yamaha
I put new sparkplugs in it it runs fine but after20 minuts i put on idle and when i give throtle it will not rev only idle it does get hot cause it pees salt water fine
any budy has avsugestion
thanks
Seascorpion

 

[kimcrwbr1]

Put it in a barrel of water and add a gallon of saltaway and let it run until the water in the barrel gets hot.