i have 2000 saturn lw1 wagon. in gear idels low and vibrates

look for a vacuum leak. it will make a hissing sound while idling. sounds like your problem.

Roy

Just to add to this one if the ac works turn it on see if the idle smooths out?If it does you need to have the ecm updated with a new calibration file that raises the idle up to where it should be.There is a bulletin for this issue have ran into it many times myself.