I have experienced that also, replacing parts, having the problem go away for a while (days or weeks), only to return without known cause. This happened after i replaced wires and plugs, and after i changed an O2 sensor. I have tried the ultimate in cheap fix attempt... clear the PCM and just drive... even that seems to help the problem, but it comes back. Maybe the engine has to be in constant edit/update mode. Unless there is a problem with the coil sending stray currents and frying the wires, i don't really think the wires go bad that fast. Everyone bashes the FMC wires, but they are definitely a step up from all stock replacement wires. My plugs show very even minimal wear each time. I wish i could test the power of the spark curent at the end of the plug wire, that would at least rule out the wires as the main culprit...
