[scarceller]

One simple test with engine fully warm is to use a good digital volt meter that can read well in the 0-1vdc range. Then simply measure the voltage at the O2 sensors signal line. If the system is functioning the voltage will swing between .2 and .8 vdc if you can clearly see this swing in voltage the system is working. If it reads a constant less than .5vdc the engine is running very lean and the system can't richen it. If it reads constant more than .5vdc then it's running rich beyond what the system can do.

And if you can get a oscilloscope you can really see that the signal is a sine-wave that swings from .2 to .8dc a few times per second. As the sensors age they respond slower and the swing takes much longer.

In Summary; measure the sensor's voltage with engine warm and report back.