I have jacked with this thing till I got so pissed off I had to walk away. I bought an Autometer A/F Ration digital gauge and Im not sure if this thing is working right at all. I had a buddy tell me to connect the signal wire directly to the sensor, then another guy tell me that it needs to be connected to the signal wire at the PCM. Well when i had it at the sensor it was a smooth motion of lean to stioch, never rich. Then once I connected it to the PCM it started flashing from one side to the other, like back and forth. The meter doesnt flow all around the dial from side to side. It will blink on the left side then blink on the rich side with one green bar. Is this the way it should read? 
But what your describing doesnt sound right.