sounds like exactly what i had happen. started flaming out when engine warmed & wouldn't restart until engine cooled. maybe i ran it too rich for too long trying to make engine last from break in but i really put stress on rod & crank? at any rate i think with my next engine i will break it in with about ten tanks, race tune & run it like i stole it! haha. does that sound like a good theory? i like to run them hard. ps. i ran it today till the end, it ran good for about 5 minutes then started losing power & i said f-it & ran it till it would barely move ( it literaly got to 400 temp oops) haha. she's definately done now!
ORIGINAL: SLAYERDUDE
While you have the engine apart you need to check the pinch, if you can easily push the piston to the top of the sleeve or thru the top then the pinch is gone and you can either get a new piston and sleeve or send it to Ray A Racing and have it pinched for around $20.
Also with the engine together but glow plug removed, you should feel some type of resistance at TDC as the piston moves thru the pinch zone.
If the engine fails both these tests the pinch (tapered fit/seal) between piston and sleeve is worn and once the engine gets to temp it loses compression and will no longer start until cool.
If you ran super rich for 1.5 gallons you also may have hammered the conrod and that will cause flameouts too.