Fuel issue , dirt or debris within the gas tank , lines or fuel filter and or carb circuits. Inspect and clean accordingly . Ensure good coil & spark plug is new ,since faulty plugs cause all kinds of gremlins !

Gas cap vent, gas tank filter etc clean the carb as you get closer to the cylinder etc. clean your gas refill tanks every few years also.

i got 2 free mowers and made 1 good unit from them. good motor on 1 and nice chassis on 2nd. i dont think former owner had ever changed air filter. had a bad coil too. used mower all last yr. worked fine. till this yr and stalling issue.

Most likely bad fuel circuits and weak coil as I advised , from the symtoms you described !

Took carb apart. Cleaned the passages. Runs fine now.

As I suspected !

fill gas tank. pushed primer. it started/stalled. primed again and it started and ran ok. it did not stall during 1/2 hr of use. so it appears to be running better. i suppose the next use will be the more definite answer. i think the main jet bolt was partially blocked.

Add some concentrated fuel cleaner to your current fresh gas ,most likely will remove any residual left over gum within your fuel system , that you may have missed .