This morning while sitting at the McDonalds drive thru waiting for my McChicken biscuits the car suddenly dropped at idle and had some backfire. Started driving and just felt sluggish and definitely sounded like 3 cylinders. Sure enough, the plug on the far right had failed. So i replaced all of them. I dont have pics yet but all of them looked exactly the same, so why does one fail out of nowhere? Weird thing is, about a year ago that same one failed after i did a seafoam treatment. I looked in all cylinders and all look the same, nothing out of the ordinary. Is there anything else to look for, just wondering why that one has failed twice now in the past 2 years? Thanks

 

did you replace your wires and distributor cap, and file the points too, that might also be the problem