Are you concerned with what the A/F gauge is telling you? Or, is the car not running right?
If it's just the gauge, I wouldn't worry about it. Those A/F gauges are worth a big pile of dog poop if you ask me.
I've got one on my Stang and never look at it any more because it doesn't tell me jack. I've got the Auto Meter gauge.
FWIW my gauge reads all over the place all the time practically. Except when I'm hard into the gas does it read a couple notches into the green (rich).
Hope this helps.
E