(2)450 DP's vs (2)750 DP's

You need to figure out what circuit you are running on when you feel the miss. are the primaries flowing or are you still on the idle/t slot circuit?
I believe that this is the area where the transition is tapering off and the mains coming in. This last change of bleeds seems to maybe have broadened that area. I may just go back to the previous tune and retest.