I have a 99 Jaguar XJ8 I have owned this vehicle for 2 years. Twice I have lost compression and the plugs have been soaked in gasoline. The mechanic has replaced the plugs and dropped some oil in the spark plug port to bring back compression. Do you have any idea what might be causing this and what can I do to prevent it from happening again

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1999 Jaguar XJ8 V8