Oxygen sensors

I just replaced the o2 sensors in the car. After replacement i pulled the codes off the computer, and it says that bank 2 (left side) has lean fuel.
Any ideas what this could be as a result of? I just got new spark plug wires in there, and i also am going to replace the spark plugs themselves in a few minutes. I figured that i take the negative terminal out of the battery and let everything reset. and see if it will do that again.. any ideas as to what else this could be? I also replace the fuel filter, air filter....
Any help is much appreciated.

Reset the computer and try again. Pull the neg cable for 15 minutes or so, recheck for codes in a day or so.

If the codes are still there, look for any vacuum leak (spray carb cleaner or ether (starting fluid) at the intake manifold where is mates to the head. A sudden change in RPM show about where the vacuum leak is. Also check your vacuum hoses. If that all checks ok, you may have a bad injector coil, or a dirty MAF making one bank "too lean" for the EEC to compensate for.

Cleaning your MAF: www.crownvic.net/tech/cleanmaf.html

Thanks for the tip.. i will get right on that.. i'm also pulling up two other codes, one of which is that the EGR valve sensor is getting too much voltage, and the other is the exhaust sensor receieving too much voltage, and AllData says that a vaccume leak could also be a cause of that.. so i will get right on that

Thanks again.

Do you by any chance think that it may be a dummmy o2 sensor? As far as i can tell (by eyes), there is no leak; however i got some carb cleaner, and i will give that a try... the engine runs really smooth, however if you put your hands on it, you can feel that it vibrates out of place at times....
I'm also going to clean the maf sensor.. do you by any chance think that the whole assembly should be cleaned by any chance? or just the sensor?

I cleaned the MAF sensor, checked for vacuum leaks.. and no luck yet.. any other ideas guys?

It turns out that there was a lot of carbon in the throttle body (almost all clogged up), and that the PFE sensor was burnt out..
all resolved now :-)