Codes 176, 543?

My check engine light is coming on and off in 5th gear on the highway, if I am just driving around town it doesn't come on although it did come on when I was driving in 4th to work the other day and went off right away. I also have a slight surging idle, it revs up maybe 200rpms to around 800rpms and falls back down to around 600rpm. I pulled the codes and got a 176 followed by a 543.
176 is Lack of heated oxygen sensor switches, indicates lean (bank #2)
and
543 is Fuel pump secondary circuit failure

but below the code 543 there is this note:
NOTE: Due to the internal circuitry of the Powertrain Control Module (PCM) , a Left/Front Heated Oxygen Sensor (HO2S) signal short to power could produce a Diagnostic Trouble Code (DTC) 542/543.

Can anyone interpret what all this means? I appreciate any help I can get thanks.

Thanks for the reply, I went ahead and replaced the o2 this afternoon and the surging idle went away but I have yet to take it on the highway to see of the check engine light will come on. I had replaced the other sides o2 sensor about a month ago when I had a check engine light that was for the right side o2 and that made it go away , hopefully this is the same thing.