99Flare, unless there is a CEL, neither Advance nor Autozone can help. Their code readers are just that, code readers. A full diagnostic scan tool, such as AutoTap, can show misfires real-time.
Pods, the way a PCM senses misfires is actually kind of neat. The crank position sensor senses crankshaft speed and acceleration. Since the PCM knows when each cylinder should be firing, if the crank sensor does see the acceleration for that instant, it's a misfire. There's a threshhold of minumum misfires (I don't know the nummber offhand) that must happen in order to light the CEL. Just b/c the CEL is not lit, do not rule out a simple misfire. Have someone help you and put an extra plug in each boot one at a time and see if it's firing. Unplug all boots so that the engine does not crank off with your hand in there. There's also a tool at Autozone for this called a spark plug tester. Not easy, but beats spending $XXX. Barring that, you could do resistance checks on the coils, but if it's not enough to trip the CEL, then they'll all probably check out ok.
Sorry if I made this too basic, but I don't know what you know about cars. Hope this helps.