Did you adjust your idle mixture? It may be too lean. Warm up engine, set to curb idle, and make sure timing and dwell are correct, then adjust idle mixture screw for highest vacuum if you have a gauge, or 1/2 turn out from highest idle speed if you don't. If idle changes more than 100 rpm readjust idle speed as necessary. Manual transmission has curb idle at about 500 rpm, it may be 750 or so with auto.
