Two weeks ago I started up old reliable, but it ran rough. I thought it would smooth out as I ran it, but it did not. I checked my codes. 1-1-1. So then I carefully checked all the vacuum lines. No leaks as far as I could tell. The engine at idle rocks back and forth on its mounts almost as if one cylinder isn't firing. All kinds of scenarious present themselves, from damaged plug, broken spark plug wire, etc., but aside from worn plugs, distributor cap and rotor needing changing, nothing I've checked could account for a sudden miss like one cylinder gone. Any suggestions, anyone? Dick