Where could a vacuum leak be on a Saturn 2003 L200?

As with any internal combustion engine, the vacuum leak can be anywhere on the intake side, including intake manifold gasket, cracked intake manifold, EGR valve, throttle body gasket and even the vacuum operated devices can contribute to leaking, such as the vacuum assisted brakes or vacuum operated vent system.
Starting fluid can often be helpful when searching for a vacuum leak; search the likely places, listening for the the typical hissing sound.
Once you find a place that you suspect of the leak, spray a little of the starting fluid. When the starting fluid hits a vacuum leak the engine RPM's change slightly.
Good luck.