Subaru Impreza GX 2002 jerking / misfiring
 

Hi since last week my Impreza seems to be jerking (misfire i think) when going up through some of the gears especially in 3rd gear. It seems to be worse when going slowly up through the gears and not so bad when driving hard with high revs. Anyone got any suggestions of what could be wrong? I was thinking either sparks, coil pack, leads etc.

Thanks Michael