1998 LSS steering has a subtle shake...

It's more noticeable when turning corners. It's just a slight back and forth pull on the steering wheel and I'm wondering what usually causes it. In the past, I believe I had the rotors replaced or changed out because it was shaking really bad when I would speed up and brake from high speeds, but this isn't quite the same. Any advice would be greatly appreciated!

1998 LSS 3800 Series 2 non supercharged

I'd say your tires or an alignment problem.
With tires the belts get vroken down from wear,
or they get turned around when rotating them, thus causing a side-to-side wobble.

Loose or bad front suspension components can also contribute to shaking.

Does it drifty or pull when you are driving straight ?

I do think the tires are do for being rotated soon from normal use. I always check the tire pressure too and make sure it's the same so it's pretty good about driving straight. Like I said, it's a really quick, subltle back and forth pull on the steering wheel, noticable when turning corners. What are the belts with tires?

Inside tires are several steal belts/bands that are connected in a "O".
In steel-belted radial tires, belts made from steel are used to reinforce the area under the tread.
These belts provide puncture resistance and help the tire stay flat so that it makes the best contact with the road.

Some tires have cap plies, an extra layer or two of polyester fabric to help hold everything in place.
These cap plies are not found on all tires.
They are mostly used on tires with higher speed ratings to help all the components stay in place at high speeds.
They even use kevlar in the side wall of expensive tires,
like run flats.

Here is a cut-away of a tire.
http://static.howstuffworks.com/gif/tire-cutaway-big.jpg

I have a 95 model LSS and there is a valve that changes the power steering from easy to sport about 15 to 25 mph. I fell it in mine when turnig wheel and excellerating (SP?). I think its normal.
Tim