318 idles rough and stumbles bad on acceleration

Failing spark plug wires. Years back my Brother had a 78 D100 with a slanty mill. It idled okay but fell on its face when put in gear, sometimes stalling. The plug wires looked okay but were apparently junk! I swapped another used set in and the truck ran fantastic!
Vacuum leak...? The Quadrajet has several screws holding it together. Check them all.