misfire - advice
 

2008 - STi
Forged API engine, HKS induction, Miltek exhaust,
Running about 370bhp, V-power fuel,
Brand new battery.

Not had it long - was giving some beans and all of a sudden bad misfire after lifting off - felt like was running on 3 cylinders, managed to limp home (less than a mile), car then stalled, restarted again ok after 1 attempt, tickover was a bit lumpy (about 850rpm), misfire seemded to have gone,
Left to cool down for an hour then went back out - everything seems normal again. Pulled well, high revs no issue, no stalling and idle seemed a bit higher (950rpm) and more settled.

Question - what could possibly cause this??
Plugs ? (these were fitted about 25k ago - NGK ILf7H) so maybe new ones needed?
MAF ?

Car is still new to me so learning what work has been done and how to live with it. (very different from my unmodded MY00 classic).

Thanks in advance..
Something else?

bump.