Given you've properly ID'd the motor with no load...
Look at page 22 & 23 of the KLS-S manual. http://kellycontroller.com/mot/download ... V1.10.pdf
Go to 4.3 (Step 3)
(1) RLS_TPS Brk %: Set to 0
Write the new setting, cycle main power off and on again. Check the setting again to make sure it wrote.
This setting mimics the inherent engine braking characteristics of a petrol motor that is in gear and rolling with no throttle. A small amount of drag is added while rolling with zero throttle to give the same predictable behavior. I've also noticed this effect is even more exaggerated when active while using the 3 speed switch in the low setting.
If problem persists, leave at 0 and try to re-calibrate your throttle input values to be more accurate and then controller won't see 0% thru 5% or 10% throttle as the same.
Page 17 & 18 (4.1 Steps 6 thru 10)
Very important that you measure and convert the voltages to Kelly's 0-255 scale (on "AC monitor" screen w/Bluetooth app) for your specific throttle
high, low, and establish accurate deadzones for both.
It is possible to just plug the throttle in, not make any adjustments and everything seem fine from the start. But if you want the best performance, take the time and set it up right.