I made a thread recently about my exhaust problems, one of those problems was that when i rev it up and hold the rpms anywhere between 1500 - 2500 rpm you hear a "thump/pop" coming from the exhaust. Its intermittent and often, and sounds exactly like if you tapped a bass woofer with your finger. The car has not thrown a check engine light. would this sound be cause by a misfire? So i took the car to my local mechanic, whom i trust, and he said it sounds like a misfire to him, he can hear it even at idle. He also says that he cannot pinpoint the exact cylinder that its doing it b/c on fords, unless its throwing a code, there is way to tell which cylinder is misfiring. Is this true? a little history: I had what i felt to be slight hesitation at 2k rpm recently until i used seafoam yesterday, and that went away... About 2-3 months ago all of a sudden the car would shudder and buck and not go anywhere quickly in all gears when i gave it even more than a 1/4 throttle. the exhaust also made a clearly audible and consitent huff/pop noise under throttle that coincided with the firing of the cylinders. So i took it to my local mechanic, had them replace spark plugs, fuel filter and do a fuel system cleaner, as i had no idea what the problem was, and it was about time for that stuff anyway. Problem went away. They told me one of my plugs was extremely foul, and that could have caused the problem. they also mentioned to me that a coil pack was beginning to go bad... I have them checking their records to see if we can pinpoint which one of the plugs was bad... So.. with that said, any suggestions or advice?