I hope somebody can give me some insight to this problem. I replaced the factory coil at around 150,000 due to some misfiring and hesitation. Once removed you could see several cracks on the surface of the coil. The replacement coil was new aftermarket. Fast forward to about 175,000 miles. Car was running perfectly then out of the blue started misfiring like crazy. I happen to have a spare OEM coil on an engine sitting in the garage. So I swap it out with this slightly used factory coil. Car ran great for about a week then started missing again out of nowhere. So I decided to try the original factory coil again just to see what would happen. And surprise it ran great for about 2 days. Well today after work I started the car and it runs like crap. I checked the wiring harness and everything looks fine. The car is only missing on the number 4 cylinder. I swapped out spark plug wires and plugs but it made no difference. Now mind you both OEM coils have cracks on the side which could let in water and cause problems. I just find it hard to believe that 3 coils have gone bad within such a short time. Help please!?