Ok, the car is throwing codes about misfires. It SEEMS, but I can't say for sure, to do this under harder acceleration.

Car has 106,000 on it now. I'm just about to change plugs and plug wires - can I assume it's just old plugs and that this will go away after the work is done?

And here is something I don't understand - I don't feel any lack of performance. Is the car REALLY misfiring? And how does the PTCM detect a misfire, anyway?