I have noticed that my sixty foot is off by .02 or .03 if I forget to "clean out" the carb after my burnout. Is this normal? Should I lower my floats? Seems like fuel is sloshing, I burnout though the lights and then have to bump the throttle to keep the car from dieing. using a double pumper with notched floats in the rear and jet extesions, I'm also using the power valve, it's kind of on the edge of opening when the car idles in gear. Car also sometimes stumbles when I come up on the two step if I don't clean it out.

I prefer to use only 2.5 or 3.5 power valves, to insure that they close off crisply, and for sure. Forget the idle vacuum, the power valve circuits only operate at wide open throttle.

If you have no heat shield under the carb, it is probably boiling out the fuel in the rear metering circuits, causing areation in the metering circuits.
I like to get my car to wide open sometime during the burnout to insure that I have fresh fuel into the rear bowl.