I'm assuming your running a Rochester M2ME

   Those carbs are a heartache, yes they do have adjustments, once you
drill away the casting flash that hides them.

     Best bet is to spring for a new carb to manifold gasket and do
the drilling with the carb off the engine.  Slot the adjustment needles
too, or epoxy a nut to the end, and use a nutdriver to adjust carb.
Some needles are already hex shaped, some have a goofy end that you can
twiddle with a piece of flattened tubing once you can get at it.

     You may consider a rebuilt carb, as those things are a nightmare
to rebuild.  The rebuilt should come with " improved " mix adjuster screws.

     A trick setup would be a 4 Bl to 2 bl adapter, the 4BL side should
bolt to the manifold, the remaining hole capped with an old
Rochester 2G  carb.  AKA the 2 Bl toilet, as it's so simple and
straightforward to service [ like a toilet tank ]

On the top of the airhorn near the front there is a knockout that
covers what I describe as an idle air valve. There are two o-rings on
it that deteriorate over time. You may be able to adjust it without
replacing the O-rings, but be prepared to do so. The idle mixture
screws may not need to be tampered with. Also, you might just bump the
curb idle screw enough to achieve the idle you need.

I would try replacing the PCV valve.