Steeda Timing adjuster causing a bucking-surging problem

I've been trying to track a problem down for about 2 years now. at about 1800-2200 rpms with light throttle application the car will surge back and forth very lightly. At WOT or above or below those rpms there is no problem. At times the car will throw codes for the front 02 sensors If I drive aroune those rpms too long. I've been playing with the timing adjuster advancing or retarding timing. When I retard the timing to 12 or 10 which is stock the surging or bucking seems to be solved. Is the computer trying to pull or add timing at those rpms competing with the timing adjuster? Have others had this problem? Is it better to get a custom tune with a chip or ECU flasher?

Thanks.

I've always used 93 octane.