So randomly my car gets about 4mpg more and the plugs are whiteish and sometimes speckled

92 LS b16 mild build uberdata and is the same with all tunes (i WILL consult the uber resources if I cant find a chassis prob)

So far I have tried:
-Boosted fuel pres to ~46-48psi
-New walbro 190lph
-no codes
-tps and MAP voltages seem to be right on the VAFC
-have tried running in open loop but car runs rich - carbon out exhaust
-took off car, 165k and still see thru (I really didn't expect that!)

I rarely hear of a well treated OEM o2 sensor going bad, but when i do, they always make the car run stupid rich and CEL. I'm wondering if a bad o2 could make you run lean... and is there a good way to check?

 

come on gurus!

 

get on a dyno with a wideband or buy a WB o2 to make sure u r running lean