general problems of the 1998 Saturn SC2

During the smog test, my car overheated but the temp. Gauge did not indicate it was hot. The temp gauge was registering that the car was running at it's usual temperature. I have always gotten my oil changed when I'm suppose to, and I've had the engine flushed to try and keep it in good mechanical condition. It also is not starting at times, and today it was making a slight jerking motion as if a fuel filter is clogging. I've replaced the catalytic converter, & a couple of sensors. Plus, my seat belts have never retracted correctly and frequently get caught in the door.