After my 85 camaro sits for a few days without being driven, it idles really rough, so rough that it shakes the car. This has happened one time before, but it ran ok when i went out to start it a few minutes later. Now, it runs rough, smoke comes out of the exaust, and it doesn't get better if i try to start it again later. It has the stock computer controlled q-jet carb, and the lg4 v8 engine. I already also checked the ignition system, but anyone who has an idea on that can feel free to chime in. Any suggestions or ideas would be appriciated very much, as i am out of ideas.
Thanks,

Sounds like a fouled spark plug. Could be the plug, the plug wire, the distributor cap, and even possibly the rotor. Less likely (but not impossible) is a weak coil or ignition module.

Or some combination of the above.

Thanks, I looked a little bit more today, and the smoke comming out of the tailpipe is white, and a lot of white smoke comes out when i start the car. Is there any quick way to find out what cylinder is causing the trouble?

If it is a dead miss, go through and pull all the wires one by one, putting them back on as you go. If the idle quality doesn't improve on one of them, that cyl. is the problem. Be careful as you do it, and use some electrically insulated pliars or you will get a nice surprise

You could also pull the plugs and visually inspect them.

Matt