May also need to check your IAC. It is suito-adjustable as if you loosen the screws, you can turn it ever so slightly. Also - the throttle blade isnt getting stuck by chance? Mine was perfect on the bench, but was sticking after I mounted it. I loosened the screws and re-torqued in a different sequence and no sticking.
I have had two intermittent issues since I installed the X-Metal TB: 1) Idle hang - every once in a while, the idle will hang at about 1000 rpms before adjusting down. 2) Low Speed bucking. Almost like the old Gen 1 bucking when the throttle bodies were not synced.