impreza 96' erratic idling

Hi there. I own a subaru impreza 96' and when i leave it to idle for about half a minute, it start to rev up and down and sometimes going so low that it stalls. Can someone give me some help about my problem? thanks

that is the cpu searching for a correct air/fuel ratio. you prolly should check o2 sensor/Mass air flow sensor/ and any other sensor that has to do with air fuel ratio. you see that problem alot on hondas when the run a straight pipe on a stock motor.

that is the cpu searching for a correct air/fuel ratio. you prolly should check o2 sensor/Mass air flow sensor/ and any other sensor that has to do with air fuel ratio. you see that problem alot on hondas when the run a straight pipe on a stock motor.

thanks 1337. i will try checking those first.