so ive been chasing this for like two weeks now and im starting to lose my mind. running a 5inch freestyle build, T-Motor F40 Pro IVs on a Mamba F55 stack. whenever i spool up past like 30% throttle on motor 3 specifically, it twitches or kind of hesitates for a split second before smoothing out. the other three motors are completely fine.

already swapped the prop on that motor thinking it was a balance issue, nope. resoldered the motor leads to the ESC because one joint looked a little cold, still doing it. ran motor test in betaflight and it does it there too so its not a filtering or PID thing from what i can tell.

havent swapped the motor itself yet because i only have one spare F40 and its a different kv. wondering if anyone has seen this with a specific ESC channel just dying partially or if these motors are known to do this. bearings feel fine when i spin it by hand, no grinding, no wobble.

sounds like the ESC channel honestly. ive had a Mamba stack where one FET was just on its way out, did almost exactly what youre describing ? fine at low throttle then a stutter right as the load came on. swapping the motor to a different pad and seeing if the problem follows the motor or stays on that channel would tell you pretty quick. if the stutter stays on channel 3 pad with a different motor plugged in, your FET is toast and youre looking at a new ESC or reflowing if youre confident with that.

also worth checking the motor screws arent vibrating loose, had that throw me off once for way too long before i noticed.

did you check desync settings in betaflight? not saying thats it but i had something similar on my build and bumping up the dshot setting or switching from dshot300 to dshot600 actually made a difference. probably not your issue since you said it shows in motor test but worth a shot before you start swapping hardware