leaks?
ok so i got a carb rebuild kit and rebuilt the carb and the diaphragms inside were not bad but i replaced them anyway along with the rest of the it since i had the kit, ran it and still ran good until i went to cut, so i did a compression test, first time read 149 2nd time 145, which from what i read is normal. is there anything else that could possibly be wrong???...... and i also tuned the H&L fuel settings
airleaks on some of the seals? Spray some carb cleaner or wd40 or something around the carb boot and seals while running, see if it changes rpms/sound.
fuel line collapsing under load demand?
coil malfunctioning as it heats up or gets used?
transient magnetic anomalies many kilometers below in the earth's mantle?
after that I got bupkis...
Under load it needs more fuel to keep running, does it get the fuel? Stop it with the kill switch right as it wants to stall in the cut, pull the plug and inspect it. Show a pic of that to the smart guys here (that's anyone but me basically), they can analyze that better than doc kildare staring at a dogbite...