Won't run when warm, needs to cool down

2009 Yamaha 40hp outboard starts and runs great all day long until you shut it off. When you do shut it off it needs about 15 minutes with the hood off before it will run properly. If you leave the hood on or don't wait 15 minutes it will start and idle but not rev up and will stall when you try to accelerate. Once it cools down for 15 minutes it will run at full throttle again until the next time you shut it off. Changed out the thermosensor assembly - no change.
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This is the old classic "vapor lock" issue. Google it.

Try letting it idle for 4-5 minutes before shutting down to cool the engine. Shut off a hot engine right away, the water drains and the head super heats under the cowling. With ethanol in the gas these days with its lower boiling point than real gasoline in the mix, you can get a kind of vapor lock with ethanol fumes in the intake creating an overly rich mix.