Replaced the spark plugs 3000 miles ago. I started having some backfire occur; so I cleaned the MAF and Air temp sensor and found the rough idle cleared. I decided to order a new MAF and Air temp sensor and left the car sit until I replaced them. Car sounded great sitting at idle. Once I headed down the road, it started to backfire and lag.

I pulled the plugs and the #2 cylinder plug was fouled and black. I replaced the plug and took the car out for a 5 mile spin. As the car warmed up things sounded as it should. As I came back into the subdivision the car backfired a few times.

Since only one plug is fouled, I would suspect that I may have a leaking injector. Any thoughts?

Brian