You're welcome.... now I need to take my own advice on my son's 340 carb LOL
Glad Mguner brought up the PCV. We had too much air flowing through the stock Mopar PCV; at 14 inches idle vacuum, it was not closing down like it should at idle; it looks like the stock PCV needs 16-18" vacuum to close down to idle level air flow. We substituted a Fram FV-191 and, voila, proper idle close down to a much smaller air flow volume through the PCV. All of a sudden, the idle mixture screws had their proper authority, and the engine idled down much better when you let off of the throttle.
