About 8 month ago, I got 1-2 misfires sometimes at WOT, about 5 month ago, I got 4-5 misfires at wot (3000-6500rpm), now I got about 10 misfires...
Old sparks? (I have changed them about 14000miles ago - Denso iridiums)
Ignition coils?
Wideband shows 10.2-10.3 and misfires don't change that.
Sometimes I don't have any misfires, sometimes I got them plenty, usually it happen, when cruising some time and then I hit pedal hard.
Misfiring stays when using NOS.
When I use acceleration pad gently, then everything is fine, when I floor it, then I got misfires(it happens every gear)
About month ago I replace MAF, but this doesn't change anything.

Where can problem be?

 

It seems like bad plugs, replace them and see if it works, also it could be a bad coil, I see them going bad pretty often., cheers.

 

I would guess plugs. Mine only last 12-16K miles. I have not used the Densos though. I understand coil is frequently a problem also. I would check coil before changing plugs. Iam also assuming no fault codes present...??

 

I've experienced the same problem. Only twice though, and have not been able to get it to do it again. No codes. Both coils and plugs are under 3000miles.

 

14,000 ago???? Plus a flash, Nitrous, Iridiums??

I vote plugs.

 

+1 plugs and/or coil packs.

 

Plugs.......I cant believe the car has not given you more issues more often