I need help? I have a 99 Grand Marquis and its acting really weird first I thought it was misfiring so I went to Autozone and had it scanned and nothing...I was mad and figured that the person didn't know what they were talking about so I went to another Autozone and the same.....I'm confused because I was told that if it was a coil or spark plug it would throw a misfire code. If it was a fuel injector it would throw a code saying a bad injector and what cylinder its present in, then I was told that it might be my harmonic balancer. The car has duel exhaust and the driver side pipe is sputtering which makes me believe that its not that, but a misfire. So if anyone can help me I would greatly appreciate it.