can't get idle lower than 1000

I've been trying to tuning my carb so that the idle is below 1000. I first checked to see if the bowls were set right and then i tried adjusting the idle mixtures. I'm going to check the vacuum to make sure the power valve is the right one. It seems as though when i go below a 1000 it wont run on its own.

are the secondaries open at idle? i know this is what was causing a high idle on my carb before...i had the idle screw backed all the way out and was still idling at 1100rpm