Holley Street Avenger 570 Idling Problems

Thanks for the input guys!! Didn't think about checking fuel pump pressure...and I did install a new fuel pump during the rebuild.
This problem didn't happen during the summer, when I first installed the new engine. It's become a problem now with the cold, and my efforts so far with the choke and jetting changes have not cured it.
I originally did not have the vacuum advance hooked up. When I tried to install it last week to a ported source, it had vacuum all the time. That's when I discovered that the idle speed had to be set higher, causing the front blades to be open too far. That's when Holley told me to crack open the secondaries slightly. That made the stalling problem worse. It you can get it to idle in gar by feathering the throttle, it's OK. Thanks. Larry