Ninjadave1400

Hi all not been on for a while but I've got an issue and I need your expert advice I've developed a miss fire, but it seems very intermittent, it's a 95 imported wrx I took of from some lights going through gears hitting 5.5k roughly through 1st 2nd 3rd fine then around 4k it missed an shock the car quite violently I got it back but shock me up didn't do it till I was on dual carriageway got stuck it outside lane trying to get out of way of ambulance and I was in 5th and gave it some to get out of the way and it did the same again.

Iveseen some threads on here about misfires but none seaming to have issues determined on gears or is this just coincidence ?