Sorta.Too much fuel can actually cause a poor combustion condition.
So can too little.
Ask anyone who's failed an E-test with the fuel pressure real low and had to turn it up to pass.
We did exactly what I suggested with Bill Savino's car at BG this year when he had the same problem as you and the car snapped back in line.
Those trends for O2's really only apply when you have all the air and fuel combusting properly.
Just keep an eye on the knock gauge.
What plugs are you running?
Engine properly broken it yet?