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Super Moderator
1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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22,980 Posts
This vehicle has COP (coil-on-plug), so there are no conventional spark plug wires. However the COP rubber plug boots can deteriorate and arc over time. Arcing will cause misfire and appear as thin gray streaks on the outside white porcelain body of the plug.
It is interesting that this happens when parked pointing uphill and makes me think that there is something wrong in the fuel tank, like the fuel pump that may be sucking air. The air bubbles will end up in the fuel rail at the front fuel injectors and cause misfire.
You don't need a 'ck eng' light to be on for a good scan tool to read 'real time' misfire and to identify which cylinder(s) are misfiring. That may be found under the OBD II misfire monitor screen.
If air bubbles are suspected, you can first test for correct fuel pressure and then take a sample of pumped fuel into clear soda bottle. The fuel stream out of the hose end should be liquid fuel with no bubbles or foam. You may want to try this before the first start of the day. Use care when handling exposed gasoline.
If this is the only problem with the car, it's a keeper.
 

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Super Moderator
1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
Joined
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22,980 Posts
Keep the spark plugs in order after removing them. They may tell a story if the tips are in different conditions as to which cylinder(s) have a problem. Black tips would indicate carbon fouling from possible rich mixtures.
You have the 100,000 mile platinums. Replace them with the same make (Champion?) and types specified on your underhood label.
 
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