Auldy

cheers will give it a bash

Thanks will try that, wher about exactly are the black and green plugs under the dash and how do i use them to reset the ECU?

Yeh its a 99 wrx sti import! Have tried octane booster and cleaned the idle control valve, also filled up with optimax since but still running with the same problem.

About a week ago i filled my subaru up with just plain unleaded instead of optimax because ther was no optimax at the pumps. the car ran fine untill the normall unleaded got in the system and engine started splutterin n' backfiring. now the engine dies and speeds up on idle, dies when puttin the foot down even jus a little while driving and dusnt seem 2 have as much power. jus wondering if anyone has any ideas of wot the problem could be before i take the car to teh garage to get checked out.