Help! Idle speed screw not working :(

well, first, look to see if the idle speed screw on the throttle linkage is actually touching anything. If it's on the fast idle cam, kick that off first. If it's not connected, you either have a vacuum leak or the secondary curb idle screw is holding the secondary blades too far open (it's on the passenger side of the carb):



Since it's too rich you should be turning the idle screws IN (there are on the side of the metering block).

I would also look for fuel dribbling out the boosters at idle. If that is occurring you'll need to lower the floats.