Yeah, the innovate ones are the ones I've read most of the stories about having to recalibrate often.
Being a dual plane, it's entirely possible one side has something 'up' at idle on just one side. Do you have a bung on both sides? Even with an X or H the gasses won't cross over a whole lot. It may just need a tweak to even things out, or one of the metering rods may not be seating.
My engine only idles with about 10" and with one step stiffer than stock the rods would bounce. With a smallish cam and 18-20", I don't see them bouncing much. Even if they did, it shouldn't affect things much at idle unless the T slot is too far open.