Questions about sensored motors.

[Desert Rc]

So I bought a lightly used Associated Vector 7.5 sensored motor on ebay. I kno I know....but it doesnt have any signs of use.

Running with Tekin RS with Tekin sensor wire trying 2s and 3s
Anyway when I try and run in at low rpm it shutters. I have tried like 4 diff lipos. Once it gets going it runs, but sometimes it takes more throttle to "unstick" from its shuttering antics.

Im not used to running sensored motors but wanted to try with my rock racer crawler.

Are all sensored cables the same?
Is there something wrong with the motor.

I trouble shot for over an hour to no avail. Any ideas?? I do have the Cap and BL RS tekin hooked up correctly. I was already using it on my cralwer with a 17.5 motor that came with the combo flawless. I just wanted more wheelspeed.