Both O2 sensors read lean, bad MPG's
I've had lean codes since I bought the car 8 months ago. But the engine is obviously running rich. MPG's are around 6.8 all city. I have new O2 sensors and they barely create any voltage. I had my car tuned today and had the sensors shut off. I'm actually getting worse gas mileage than before. On the hour trip there I got 14.7mpg, on the way back it was 13.1. I don't know what else I can do about this, and I don't know why both of my sensors would fail at the same time. The stealership and Dyno guys had no clue either. Anyone else have the same problem or have any ideas?
Mods: SLP Lt headers, SLP exhaust with high flow cats, Vararam CAI.