02 Readings Low???

[TrAb]

Hey guys, at a warm idle my car is staying right around 350-400mv. Is this normal? The car had been running well for a while but just recently started getting a slutted at WOT. I JUST replaced the 02 sensor about 80 miles ago. Thanks

 

[TrAb]

Car was out of gas, gauge must not be working to good...