new carb issue on old carb...

[mater69]

So I recently rebuilt my holley 4160 vac. secondary carb. Everything was good until recently the motor won't idle correctly. It surges real bad and won't hold an idle. So I checked for vacuum leaks with starter fluid, and that all checked out ok. I then tried to adjust the idle mixture screws. They are not working, and when I screwed them all the way in(closed), nothing happened there either. I suspect a bad power valve, but not sure. Isn't the motor supposed to die when I screw the air mixture screws all the way in? For the life of me I can't figure out why my idle circuit isn't functioning at all. I checked to make sure the butterflies were in the correct position, so as not to be past the transition slot, so what gives?? I also checked the float level and it is good too(just a small trickle when sight plugs are removed) Any ideas?