Holley 750 DP idle question

1st off, love the car. 2nd, i have no first hand knowledge of how a blow thru carb operates, so i'm just spit ballin' here.

When i saw that you played with the 4 corner idle and saw some temporary results it had me thinking it may have been acting rich? If so, is there a chance your fuel pressure has increased for some reason. Maybe a faulty regulator if your using one?