Newbie, Yes you could have a vacuum problem. Most 20 year old cars do. But also the air flow meter may need to be adjusted. Since the 02 sensor is a two wire w/o a preheater, the Idle will be a little rought till it warms up. Then 02 sensor thru the Lambda/ECU will adjust the Frequency valve to adjust the air/fuel mixture. After it warms up and you still have the seeking Idle, I would adjust the air flow meter. You can see a lot of info on my web site about it. John Hervey http://www.specialtauto.com/fuelsystems.shtml