FTO GPX running rough intermittently

[Taeivon_Rep]

Hi guys,
Got a problem with my 95 GPX manual. Whenever i start up it runs fine but sometimes it will cough and splutter and hesitate to accelerate and engine light flickers on during that time. After about 30 sec and a gear change or 2 it runs fine for a while. Doesn't happen every time i drive though. Started 2 days ago.
Looking for some advice, im thinking it might be either the fuel filter.
Somehow picked up dodgy fuel when i was in qld..
or Dirty air filter or o2 sensor?
I'll take it to a mech on tuesday to see if they can check the codes and find something out.
Help would be great thanks.