The Nissan Path

I have a 99 pathfinder and have check engine light on and horrible gas mileage and vehicle smells like gas at the exhaust
codes are-P1168
P0151
P1148
P0131
Any body have any input? do I replace O2 sensor? any thing else?
Thanks!!!!!

P1168 & P0151-Left bank, front oxygen sensor
P1148 & P0131-Right bank, front oxygen sensor

Refer to Nissan TSB #NTB99-004B. It details a testing procedure to test the resistance of the EGI grounds at the upper intake plenum and gives info on a supplemental ground harness and installation.
Since it smells like gas, you may want to check for leaks and/or excessive fuel pressure. It's possible that you have two, bad front oxygen sensors, but start with the TSB first.