I wish I remember the year to year variations on the tank internal layouts better, but I know that certain years, the way the slosh cup is setup, if you have a big enough pump setup (which you certainly do) you can basically empty the entire cup on a run because it doesn't fill back fast enough, and go lean, despite still having as much as a half tank of fuel still.
I hope this won't be the case for you . . . but, if you are still having issues with that setup, then you at least know where to look.