How can you trace a vacuum leak on a 2001 Saturn sl?

The way I do this is old school.

Examine all vacum lines, conections, Ts lines and accessories.

Start car and listen, sit in drivers seat with door closed and listen with stereo and heater off, turn heat on fan on lowest setting, change to all heat cool and defrost, foot and AC outlet settings.

If by now you have not heard a hiss from a leak then the next step must be performed outdoors on a fairly wind calm day. Take a propane plumbers torch. Turn it on so it leaks propane with out lighting it. Move slowly past intake gaskets, vacume lines and accessories. The engine note will change for a split second.

Good Luck