Sea Cruiser 7 hp help

[murph]

I just ran this motor for the

I just ran this motor for the first time this spring and it started up just fine and ran. Once the motor is warm and I try and start it up it stalls out and when it does run it has a very rough idle. It also has considerably less horsepower when this happens. But it only happens when the motor is warm. I also changed the spark plug and this did not help.

Thanks