Stalling Astro Van

I have a 1992 Chevy Astro Van that keeps stalling out when idling. It also runs a little rough while moving at slower speeds and runs worse in the afternoon when it’s warmer out. At first I thought I had a little water in the gas and added a bottle of dry gas. I have also changed the fuel filter, spark plugs, and idle control valve. None of that worked. Any ideas?

Have you checked the fuel pump pressure? This sounds a lot like low fuel pressure.