You can set the ramp rate in the Jag if you are using CAN bus.
If you are using PWM, you can enable the fixed ramp rate of full reverse to full forward in 1/8 second by placing the limit jumpers parallel to the front of the Jag. See Pages 2-3 of this document.
Or you can put the very simple code shown here to limit the rate at which your joystick command is allowed to change. That will limit the rate at which your Jag changes voltage.
You can try it, but I do not think ramp rate is your problem.
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