Holley Idle Screws Not Responsive

I'm having problems setting up my new Holley 750 DP (4779). The problem is that it seems to run pretty good (maybe a bit rich) but there is no response from the idle mixture screws.

When I first installed it, the screws DID effect the idle but the primary bowl was overflowing with gas so I cleaned some grit out the needle and seat and readjusted the float levels but now the mixture screws DID NOT respond.

Next I took the carb off of the car, cleaned both bowls, metering blocks and the body completely. I blew out all of the passages with air bought new blue gaskets and put it all back together. Still running pretty much fine but no change in the mixture screws.

I took the carb off again, and re-cleaned everything and made sure the gaskets were all correct. Again, no change. Next I took out the new blue gaskets and put the original blue gaskets back in (just to be sure) and still no change.

I checked the timing to rule out any sort of issues there and its all fine. The throttle plates look to be undamaged and closing properly. I have run out of things to check. I'm past what I know about carbs. What can it be?