The A/F gauges that work with your stock O2 sensors are not accurate enough to tune with. These gauges run about $50 and have LED's in them that sweep from "rich" to "Stiochoic" to "Lean" just tell you which side of 14.7 A/F you are on.
In order to tune your car, you will need a wideband O2 sensor tapped into your exhaust with a numeric read-out that displays the actual A/F ratio. This setup costs about $600.