Boy, did this bring back memories! Years ago I put a new intake on my old 340 and couldn't get it running good for anything. The intake had been drilled for multiple carb mounting bolt patterns and one of the holes I wasn't using for my Holley had been drilled through into a runner. That sucker had the biggest vacuum leak, but you couldn't hear it without the good old rubber hose 'stethascope' stuck in your ear.