Slant hesitation

So, I have a 1974 slant in my Duster, and I went to a car show last Sunday. After waiting in line idling about 30 minutes she shut off on me. Seems like when I get in traffic, and she warms up the hesitating starts. Runs fine when cold. I checked the vacuum hoses and everything looks good. Put a rebuilt carb on and adjusted the mixture screw about six months ago. Hesitation still there. Any common problems you guys could suggest ?