Hi my 86 Si civic ZC engine is cutting out between 4600-5000rpm. It is only doing this in first gear. I have new spark plugs, new dist cap and new ignition leads. the previous owner informed me that the ecu was replaced. The ecu is a pg7-033. i think this is a integra ecu. I am getting a code 1 fault code as well which is the oxygen sensor. Has anyone got any idea what may be causing it to cut out?