Long story short... I hired a mechanic to fix a problem on my starboard engine and he Installed the petronix ignitors (converted my old points setup to electronic ignition using the old distributors) on my 1987 crusader 454's, and now my port engine will not run right. Starboard engine runs like a champ. same sensors, same exact setup. Only difference I can see is the starboard engine has a new ballast resistor whereas the port engine has an old one. NEVER had a problem with my port engine until the petronix, it was always my reliable engine. I've narrowed it down to this. I know it's not the sensor, because I tried two of them, and I highly doubt they would Both be faulty out of the box. I know the timing is right because we checked it with a timing light. We hooked the timing light up to each spark plug wire and on two of them there was an intermittent pause in the light sequence, which indicates a problem. It's just weird how everything ran perfect until this. So far here are the things im going to do: 1) Replace spark plugs, cap and wires 2) check grounding wires and ensure distributor ground clip/bolt is clean and no corrosion Does anyone have any advice on this? OR has anyone ran into the same problem?