car shakes at idle

hey all,
two days ago this started. when the car is cold and idling, there is an intermittent shake. Not just a vibration or rough idle--the whole car actually shakes a few times and you can see it move. it kind of feels like shifting gears, but of course i'm idling. once warmed up, the problem goes away. it does this in neutral or drive; haven't tried putting it in park at a stoplight yet. no idiot lights. it doesn't seem to do it while moving but it's hard to tell since the roads are so bumpy around here...

it's a 96 Lsi with ~91k on it. what do you think? spark plugs/wires (plugs and maybe wires replaced sometime before 75k by PO)? vacuum hose? O2 sensor?

thanks,
dan

[Chicane]

Sounds like one cylinder isn't firing. Check your plugs. That's my suggestion. >shrug<

- Rob

[svx_commuter]

It might be the temperature sensor a miss when cold would still be missing when hot. Quite a few people have had problems with the temp sensor and cold starts. Try a search? How often do you use fuel injector cleaner?