I too run Jackal and know first hand that .63 V is too high, you should be between .48-.52V in order to read 10%, at least mine does in Jackal. Backing the closed idle switch out a turn will only make matters worse since it will not being reading in the proper range or not at all.
You must first properly adjust your closed idle switch with the throttle cable loosened.
Second, adjust your TPS (.48-.52V) with the throttle cable loosened.
Third, adjust your BISS screw.
Fourth, set your timing.
Hopefully this will help, it sounds like you may be a little off on these "finicky" adjustments & I know first hand how much it should help with your issues. Once I learned the proper adjustment & sequence my engine ran/idled much smoother and I don't have any of the troublesome issues people generally complain about relating to the subject.