Since you found improvement with the .031's, then retest with the .033's. You will need to reset your in D vacuum again.
Then test with the different IAB's that you have.

Since the IFR's and the IAB's work together, look at the IFR's as your "internal adjustment" and the IAB's as your "external adjustment". If you have three sets of IAB's, then test with all three to see if it makes a difference. If the three sets that you have do not give you the results that you want, then open the carb and change the IFR's then retest with the three sets of IAB's again if needed.
You usually want to change the IFR's in small increments (.002-.003" at a time). The IAB's can be changed in larger increments (.005" or so).

I would test your smallest IAB's along with the .033 IFR's. If your smallest IAB's are not small enough, then take a small wire and insert it down into each of the primary IAB's and bent the top of the wire so that it goes down into the carb body so it will not fall out. This will reduce the IAB hole and allow you to test a richer setup before buying more IAB's.