Your 1993 has just one O2 (oxygen) sensor (1996 and up have two, one after the converter to monitor the catalytic converter). It is used to set the mixture precisely right. The Engine Control Computer guesses how much fuel to inject based on the MAnifold Pressure sensor (MAP) but that results in poor economy and poor power. The O2 sensor, mounted on the front of the exhaust manifold, provides feedback several times a second to keep the mixture exactly right. As the sensor ages it becomes sluggish. A new one will transition between rich and lean seven or more times a second, but as the sensor ages it slows down. Imagine trying to drive with a half second delay between turning the wheel and feeling any effect and you get the idea. It is often most noticeable when you change the throttle, like pressing it for a bit more power. The engine has to wait for feedback about the amount of fuel to inject at the new setting if the sensor is sluggish.































Early catalytic converter cars didn't have O2 sensors, but ran rich and injected air into the exhaust to burn the carbon monoxide. That gave catalytic converters a bad name because the fuel consumption was terrible and the power was significantly lower - just as a modern car is without a good O2 sensor.