Your car shouldn't shake in the first place. Then again with that millage it just might...
Shaking is generaly a sign of a misfiring cylinder.
Do a ghetto tuneing check. Put it in park start it up and see if the engine vibrates "hard". (Just start it cold and put your hand on it) You can generaly feel an odd bounce if a cylinder is misfiring.
If your engine is perfectly tuned you should be able to balance a coin on it. (That's the ideal scenario, as in brand new car)
Well, first of all, thanks for all of you answering my question. Actually, my Vision doesn't shake at idle. But it just seems that when I put it to "N", my Vision stable and silent just like the car hasn't started up yet.
Shouldn't do any harm but I would think that it would just be alot of extra work on the trannies solenoid pack, so I would do it only if I was going to be sitting at a stop light or something for more than a minute or three.