[81turbota]

Are you setting your idle mixture with a vacuum gauge? With what you're describing I would expect the gauge to be wandering all over the place in the low range at idle.

Sounds like a carburetor issue. Check fuel well plugs as pointed out, if you pull the carb and it's soaking wet underneath they're leaking. Fuel pressure as well. They can be epoxied. Check the choke mechanism and make sure it's working correctly on the cold-hot transition.

Adjusting the mixture screws before verifiying fuel pressure and leaks will be an excersise in futility. They won't do much if the fuel is being pushed past the needle.

FWIW I love quadrajets on street engines. I will tune them but let Sean Murphy rebuild them for me because he does some additional internal modifications that wake them up.