If the Check Engine light is on, and you have no drivability issues, then more than likely this will be an EVAP (emissions) system issue. Seeing as there are so many sensors/parts within this system, taking a "guess" isn't very efficient. The best place to start is at your local Auto Zone. You need to have the codes read from the computer, and Auto Zone will do this for Free. Once you have these codes you can more accurately determine which sensor/part in which system has the fault.
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with your model of Z car the evap codes don't really apply because its too early for them those codes are typically on cars from 96 on up on your vehicle the most common codes that come up are the o2 sensor codes and on occasion an egr code and every once and a while you get a code 45 for injector leak but I doubt that one since you have no drivability problems however the egr and the o2 sensor codes can be set and no real drivability issue detected - the egr code can be the most difficult one to repair because when it sets its usually the egr tubes under the plenum that are clogged and they are real trouble to get out and clean