Hi, this is my first post on this website, just so you know. I own a 96 Mustang V6 auto with 207,000 miles. For 8 months, my check engine light has been going on and off. The first few times it was a "cylinder 2 to misfire" error. So I replaced the spark plugs. Then a "cylinder 4 to misfire" error came up, so I used fuel injector cleaner, seafoam, and complete fuel system cleaner, also I replaced the spark plug wires about 200 miles ago. The check engine light came on again with the error for both cylinders. What's the next step?