Another thing to think about is: if the center carb idle speed screw is screwed too far in, it will expose the transfer slot and the idle mix screws will become ineffective. So right now, if you screw the center carb idle mix screws in all the way, does it cause the eng to stall?

1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.