Vapor lock/ sticky float?? 30HP JOHNSON 2 STROKE

[73 Dolphin]

After running my early 90s 30 hp Johnson 2 stroke at medium to high throttle for a while (20-30 min) it will tend to splutter and stall when coming back to idle speed.
Then any attempt to restart it fails.
I'm thinking that if I kept the revs up I could run it all day. It only happens when coming off the throttle to idle.
After 2-3 hours of sitting and sometime overnight it will start again.
Changing the plugs wont start it either once its decided to stop.
Does this sound like vapor lock/ a sticky float or another issue??
I did recently change the thermostat in case its over heating though I have never heard the overheat alarm. Water pump impeller is also very recent.The engine will crank but not start.
Ill rebuild the carb this weekend in case its a sticky float or similar but figured it would hurt to ask you fine folks what you thought.
It would be nice to use the motor on the way out and also back in and not have to rely on my trolling motor.
Thanks!

 

[Crosbyman]

if not a fuel issue could still be localized overheating issue did you check for heat related problems ... could be overheated ignition components.

try some coolant spray* to cool down the ign. coils just to see it/they reacts (starts up again ...before the next morning

try other componets see if any come back to life.

* keyboard duster spray can from Dollar store held upside down cools things pretty fast .

 

[jimmbo]

Is the Spark Healthy enough to Jump a 3/8 inch Gap on both Cylinders?
Is the Fuel System Clean? Fuel Pump good, as in no cracks/holes in the Diaphragm?

 

[racerone]

Test run with another tank and hose.