1st, Are you sure this truck is an ECS version?
Usually the O2 sensor itself is not what is bad, but the correctly reading o2 sensor see a 'bad' reading due to lack of good tuneup or other failure like a clogged catalytic converter.
what made you decide to try and set the air fuel ratio (this is actually something the engine control is going to change while running with respect to changing inputs)?

next, let me ask how you like using the Toyota analyzer, and do you think it is worth it? (and may I ask where you got yours?)