New motor/1050 dominator won't idle

Update: next day-noticed back bowl was filling too much. Adjusted.
Adjusted fuel pressure to 10 PSI (it was much lower)
Idle mixture screws backed out to 2 turns each.
Now starts clean and will idle at 2000RPM, but any attempt to turn mixture screws in results in engine slowly dying.
Idle RPM screw is all the way out, RPM will go up if I tighten it but won't come down.
Vacuum leak??