The CEL is a signal by the "On Board Computer" that a problem is sensed. There are many reasons. The light will go off if the computer no longer senses the problem. The computer will register the problem as a code which is put in memory. The computer will remember the last several codes. The CEL is related to emissions problems, many which can result in poor driveabilty and performance. The O2 sensors in the V6 are a common problem. After about 50K miles they are prone to vary. This tells the computer that there is a problem. There may not be an engine problem, but rather a "sensor" problem. Bad thing is that the computer may "believe" the sensor and adjust something else, resulting in poor performance and gas mileage.
Anyway... it's common for the light to come on and go off. As the problem worsens(they usually do), the light will be on more. Take the car to a dealer or other service center to get the codes read and diagnosed. Some auto stores will provide the code reading (and maybe advice). Good luck.
Al
