Rover overshooting input in manual mode?

As the title says I’m having some issues with mostly stock Rover 4.1 dev (needed for FPort receiver). For some reason when I’m in manual mode and driving the rover I get some overshoot from what I’m inputting, like it’s trying to lock to a heading and doesn’t stop until it gets there. I also notice when I bring the sticks to zero throttle it’s a while before it actually cuts off the ESCs. Compass is disabled and there is no GPS installed.

Is there any way to prevent this and make it act like it’s directly connected to a PWM receiver?

It might be worthwhile checking and experimenting with the settings limiting rover acceleration and/or motor slew rate. I am unsure if these parameters have any effect in manual mode.
See at the bottom of this page:

Manual mode is simple passthru but right throttle slew applies.

I suspect it might not be determining the speed to cut throttle fast enough, not really sure. I don’t think slew should keep it running. I might try messing with accel settings and see what happens.