I need a little help!

I've installed an AEM 30-4900 wide-band gauge.

And got this:


Tried to adjust the CO pot, but never got better values

12.9-14.3 AFR @ idle
15-18 AFR @ low acceleration, -0.3 bar
15-13 AFR @ 0 bar
13 AFR @ full load

What can I do to have a richer AFR?

Thanks!