so this has been driving me crazy for about two weeks now. got a 5inch freestyle quad, running 2306 2450kv motors on 30x30 stack, the rear left motor just randomly cuts out sometimes. not every flight, maybe every third or fourth one. when it does the quad just lurches and drops like 5 feet before i catch it on the sticks.

ive swapped the prop already thinking it was a balance issue, no change. the weird thing is if i do a motor test on the bench with betaflight it runs totally smooth and consistent, no stuttering or anything. only seems to happen under actual load when im doing fast direction changes. temps on the stack feel fine after flights, nothing crazy hot.

my gut says its the ESC but idk if thats just because its easier to blame the ESC than pull the motor. anyone dealt with something like this before? wondering if i should just swap the whole stack or if theres a way to actually diagnose which one it is before i start throwing money at it

pull your blackbox logs and look at the motor output for that rear left channel right when the dropout happens. if you see the FC commanding full throttle on that motor but rpm drops anyway, its almost certainly the ESC losing the signal or a FET going bad. if the FC output looks weird or its not commanding anything unusual then you might be chasing a motor phase issue or a bad connection at the motor bell.

also check your motor screws. sounds dumb but i had almost the exact same symptom once and one screw had backed out just enough to let the motor shift slightly under load, messed up the air gap and caused intermittent stutters. took me forever to find it.

could also be a cold solder joint on the motor pad. i had one that looked totally fine visually but was cracked underneath and only made proper contact when the motor was sitting still. under vibration and load it would just lose connection. reflow all four motor pads on that ESC corner and see if it changes anything, doesnt cost you anything to try before buying new parts