Let me put it this way.

The car is always trying to reach stoich, so when it use's the o2 sensors that is what you are seeing. They go lean to rich and never stop doing that. So when you see it on a wideband the numbers bounce around from 14-15.3ish as stoich is 14.7. All of that is completely normal to see. Now if you were going WOT and you see the WB going from lean to rich and so on, then you have an issue.