@stuart_as When you pulled the spark plugs was there oil in the spark plug holes before pulling the plug ?If so the valve cover seals are gone and the plugs are being drenched in oil . to remedy the problem you need to replace the o-rings in the valve cover spark plug passages. when drying up the plug its a good idea to put dielectric gel in the spark plug boot as this will help seal out the moisture. but oil filled plug shoots will keep the car from running . Hope this helps