Carburetor not working properly

My Slant Six has a 1 Barrel Stock Carburetor and it seems to be working fine. But my air intake fits right but because of low idle and sometimes shuts off. If I put pressure on the air intake, then it idles fine at the right RPMs. But if I let go it acts stupid as if it’s getting too much air and if I hit the gas it sputters like it’s pulling too much air. How do I fix this problem?