I finally had some spare time pick up a multimeter and test things.
I plugged the positive into pin 2 and the negative into pin 3, and got a reading of 38%. Have I done this correctly?
According to Steve's article, this indicated a rich running engine. No flucuation would indicate a dead 02 sensor.
As I indicated before, my car runs great before it warms up, but once it reaches operating temp it becomes sluggish. What should my next step be?
Thanks again for all the advice, it has been very helpful, and will be to everyone else with this problem in the future.