update: random cylinder misfired

[NISMO SER]

Hello All

A couple of weeks ago, I posted about my car having random cylinder misfired
causing my check engine light to go on.  I've done the regular tuneup like
changing plugs, caps and rotor, fuel filter, O2 sensor but didn't change out
my Magnacore wires.  the check engine light would go on and off when it
feels like it.

Funny enough, after I sent out the post my check engine light went away.  A
couple of days later I went to the local dealer and bought a set of new
stock wires and dumped the Magnacore wire.  I installed the new stock wires,
fired up the engine, that damn engine light went on again. This is weird.  I
drove the car for a day and the check engine light disappeared again.  I'm
scratching my head here.

I drove the car for another couple of days with no check engine light, 350
miles later, the damn check engine light came back to haunt me, then one day
later the light disappeared again.  There seems to be a pattern of what's
happening, it seems to me that for every 200-400 miles the check engine
light would appear once then disappeared after 1-3 days.  This has been
happening for about 9 months now.
Any ideas guy?

BTW, after I installed my new stock wires, my mpg went from 19 to 20 :)

thanks
David
98 SER
S3 cams, HS header, custom exhaust etc...