My inclination would be to install smaller idle feed restrictions - primary side.*
it would be good to know how much transition slot is showing at idle.
This is an Avenger 770?
Could be slot is too wide or too long.
Even if it is, I'd still start with with primary idle feed restricitons.
You didn't mess with the secondary idle position. right?
*It's easier to install threaded IFR than to press in new ones.
Before you do, might as well map out the various holes and restrictions.
It is possible the Idle Air bleed or a passage has something goofy going on. Shavings - a hole not drilled - you never know.
If the engine idles with less than 12 or 14"hg, its going to flow noticible more fuel as the engine gets more vacuum - up to around 14" when flow through the restriction will max out and things will act normal from there up.
This why I'd head toward IFR based on what you have written.
You'll need a pin vise and small drill bits to measure the holes (use the shank) and to bore a hole in the a brass set screw.
Hold the screw in the jaws of the drill. Go slow.
Also a tap set with bottoming tap.
Lots of info here
Relocating the Holley Idle Jet
How Are You Drilling Your Set Screws?
