From time to time under WOT at about 3000rpm I think I detect a slight mis-fire for a moment or two.

Would a mis-fire cause any codes to be logged which could be read by a regular OBDII scanner ?

Engine has about 20,000 miles and is still on original plugs so I'm considering changing them and maybe the coils while I'm at it.

Might be bad gas - so will run it low then re-fill with some other brand /source.

Other than this slight mis-fire everything else seems 100%

Any thoughts ?

 

Misfire should log a code. Not sure if it needs to be enough to flash the CEL or not. Not sure if a regular OBDII will read it, but Durametric will.

I had misfires and there are codes as to which cylinder, etc. But my CEL would flash when I got them...

Hope that helps!