Xenon

Hey guys, I've noticed lately my Altezza RS200 feels like it is misfiring under WOT situations - just a few slight hiccups, but revs continue to rise and feels OK apart from that. The current map has two fuel/ignition tables for 95 and 98 octane fuels, occurs on both maps. Seems to happen further up in the rev range past 4.5k. Have just replaced the spark plugs and noticed no difference - same as before, using NGK BKR7EIX-11 plugs which were put in 2 years ago for the initial tune, and one heat range colder than the stock BKR6EIX-11 plugs. Coils don't look burned out or have any signs of arcing. Have attached a log of a few pulls to 100 km/h but can't spot anything obvious, though the car hiccuped each time. At some places during each pull the injector DC% drops while Fuel Table 1 number rises so not sure if this means much? I've upped the ignition dwell times slightly to see if weak spark could be the cause but no difference noted. Would appreciate any advice. edit: all resolved by regapping plugs and replacing all four ignition coils Cheers