Is it normal for O2 sensor output to read 0.004mV during while crusing til I let off the gas? Most of the readings is above 0.450mV I increased my fuel pressure so I won't run lean up top until I change to a hi flow fuel pump during a rearend swap. I hope it just a bad sensor. Thanks

 

I have no idea how you generated that data, but I suspect it's doing a calculation of some sort without enough logged data to make for an accurate calculation/result. or maybe it's just some kind of rounding error (0.004 is very close to 0) in the program you used.

Either way I doubt it's an accurate representation of what's actually going on.

looking at actual logged frames in sequence will be very helpful for you in this case. during closed loop cruise, you should see o2 sensor voltage jumping all over the place generating cross counts.

 

I was datalogging with winaldl program.

 

That's an incredibly hard way to read the O2.
The O2 voltages flucuate as the ecm tries to toggle across 14.7:1 to maintain an AVERAGE AFR of 14.7. So you should see it moving above and below .45v.