rough idling/rpm fluctuating

Hey everybody! Just joined. Have a small problem

When I stop at a stop light, my car seems to vibrate a little more then it should. It doesn't vibrate continuously, but seems to kind of convulse every couple seconds. The RPM seems to fluctuate from 800-600, too.
*The car does not do this when in neutral
*Just did a tune-up with wires/spark plugs a week ago (thought that would solve it)

Car year/model - 2001 Saturn SC1
Mileage - 60,000

Any help/suggestions is greatly appreciated

(I also have another problem with it wobbling as its driving... should i create another thread for this?)

Spark plug type?

Change your ECTS. Yours is possibly resin and already cracked. Brass ones are best bought at the dealer, but can be bought at Advance auto, az, nappa.

Clean your throttle body. Remove all the carbon build up.

Wobble? More info is needed. Does turning make it worse? Which direction? Have the tires been re balanced?

Thanks for the feedback! I'll try those as soon as i get paid on friday

Wobble? More info is needed. Does turning make it worse? Which direction? Have the tires been re balanced?

Hmm, doesn't seem to make it worse when I turn. I'll be driving on a perfectly new/level road, and It'll kind of dip to the side as if i was driving over a bunch of small hills. Seems like it happens on the left side. Haven't had the tires rebalanced since I've had it (3 years)

Check your tires. Id rotate them and see if the symptoms follow. Dpending on the tire tread left, id get new tires or get them rebalanced. Its possible a weight broke off in the past 3 years