As far as the reason for wanting to adj. the fuel mixture. The distributor was bad so I replaced it. After I got the truck running the idles were off and it didn't seem to be running correctly. So I thought to check the mixture to see if it was correct. The analyzer was provided by my place of employment. I think the analyzer was helpful to me. Although I could not get it to were it would read the mixture and injection period. I will check the vacuum connections for leaks and see where that gets me, also the voltage at the o2 and use that as a ref to the mixture.

Check for vacuum leaks at the intake manifold...also,check your air tube after the air filter for cracks and opens,you are getting more air than the engine needs someplace.....

Induce a lean condition, remove a vacuum hose...O2 will go low at.1 volts. Now go rich by adding fuel...with propane bottle at intake...does the O2 sensor show high at.9 volts? If so it's seeing the mixture. That's all it does. It reports back to the comp....and the comp make adjustments. It's just a messanger, it goes high and low according to the comp output. If the ECS does not respond then you have other issues. Remember, Low voltage on any O2 is LEAN. High voltage is RICH

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?)