1988 Pontiac Grand Am Engine Stumbles

Engine Performance problem
1988 Pontiac Grand Am 4 cyl Front Wheel Drive Automatic

I have a 88 grand am 2.5L. The check engine light will come on at idle and "sometimes" the engine runs rough then will stop running rough and run fine. But the check engine light will go off when you start driving but "sometimes" the engine will stumble while driving other times its perfect.I have replaced the fuel filter and map sensor.

Thanks