Understanding Air fuel ratio sensors (wideband)

This is a generic question regarding AF sensors.

On my non-Ferrari two bank toyota daily driver, It has two AF sensors that report anywhere from 0 to 5 volts (nominal) when engine is running and at temperature. On one bank, a brand new sensor I installed a few weeks ago reports 3.3 volts rock steady. It varies at most from 3.1 v to 3.7 v.
But on the other bank, the real time reading swings all over from a low of 1.2 to a high of 4.7. It averages around 3.3, but wonder if it is a faulty AF sensor? It is about 4 years old but only 10,000 or so miles. Car is 20 years old and just runs so I've kept it.

Is this normal?

Car idles fine, no DTC codes whatsoever, but there is a hesitation on hard acceleration off the line (no issue above 2,000 rpm). I run with Shell gasoline same as the Ferrari (nitro).

 

Good idea - only issue is getting to it (close to firewall, require a lift to get at it from underneath).
I know the coilpak's and spark plugs are good ... which leaves 20 year old 100k fuel injectors. I wonder if one or more of them is sluggish/dirty) causing the hesitation and swinging AF sensor voltage. Fuel trim on this bank also swings quite a bit (+/- 10-15 %).

I thought about a professional fuel injector cleaning, but read it's mostly hype. This car does sit around a lot and I did put red line through it with no change.

I'm just guessing before I decide it's time to get rid of the car.

(my wife can't imagine why I keep this thing (2000 lexus), but it just runs and looks great still (interior is mint)....that is...up til now.