[NiftySVX]

The real trick with the select monitor is knowing what it is telling you. This is more of the advanced stuff that isn't really common knowledge. Having said that, I am confused as to why you are condemning the oxygen sensor.

The purpose of the sensor 1 position (pre cat) oxygen sensors is to provide the ECU with data so that it can fine tune the injector pulsewidth to ensure optimal fuel delivery. I.e if it is lean then increase injector duty and if it is rich then reduce. This is commonly called "fuel trim"

The oxygen sensor is likely showing you information you need to use. It may be telling you which side is off. If you actually hydrolocked the motor it would likely have bent rods and then you'd be really in trouble. But that's alot of liquid to get in there to cause that to happen. If your 02 shows rich on one side then you could assume there is an ignition misfire or a leaking injector, If there is a lean condition you could assume that there is a fuel delivery problem in that bank.

I don't recall if the old select monitor provides you with fuel trim data, if it does that is what you want to see. If the computer is telling bank 1 to increase to 20%, say, then you'd know the computer was trying to add fuel to it. Or if you had a leaking injector, it would say -20% or so, and it would be trying to lean it out.

RH bank is oscillating around .5 v, this is normal. I would assume that your RH bank is runnin pretty good.
LH bank at .4? Sounds pretty lean to me. Are your injectors firing on the LH side? is one clogged? do they have pressure?

Of course there are other possibilites that could cause these symptoms (including a bad O2)but based on the fact that you have plug/injector issues that's where I start.
If possible I would look at the scope pattern of the sensor.