My van shimies left and right badly....and it pulls to the left....it does it more when going straight and not so much when going around curves

That's a mess. Something is bent in the steering or suspension linkages. The tire is scrubbing because the wheels aren't pointing straight. The CV Joints also need checking. Your vehicle is dangerous to drive.

Are you sure the lug nuts aren't loose?

Do you happen to have plastic rim covers? An auto mechanic suggested that these can rub or oscillate in just the right way to make you think you have a permanent rock stuck in your tire treads. It drove me nuts! But sure enough, I removed the rim coves and there was no noise at all. I ended up putting the same ones back on again with double-sided tape (double layered) along the inside rim of the covers and this stopped the noise for some time. Alas, one winter later, I'm hearing noises again. I've pulled them off again this week, but with my black rims underneath, the van looks like some undercover cop car!

Most likely it is a Hub bearing worn out. If you have access to a highway with a sweeping curve the outside tire turns faster than the inside tire following the curve. So if the noise increases on a left curve, the right side is bad. If the noise increases on a right curve, the left bearing is bad.

You did not state whether you have 4 wheel drive or 2 wheel drive.
The 4 wheel drives have the Hub bearing. Check around for parts prices. The price can vary by $100 from store to store. If you have the 2 Wheel version it is much cheaper to replace and you will need a wheel bearing seal.

Do spend a little time checking the other components in a 4x4 as the additional components can also make noise.

Tierod ends. Bad belt in a tire. If you have a bumpy brake pedal, a warped rotor has enougn play to bounce against pads. Also Hub bearings were known to fail after 35,000 miles.

For Hub bearings there may be a Service Bulletin, but your vehicle is going on 10 years old. Usually the side that shakes the most on a opposite curve is the problem side. As in left curve the outside right tire is spinning slightly faster, right side curve its the left side spinning faster.

CHECK POWER STEERING FLUID IT COULD BE TOO LOW.OR YOU HAVE INCORRECT TIRE PRESSURE.LACK OF LUBRICATION AT STEERING JOINTS.YOUR FRONT END OUT OF ALIGNMENT.YOU COULD HAVE A FAULTY POWER STEERING PUMP.OR YOU HAVE A LOT OF AIR IN POWER STEERING SYSTEM.YOU HAVE TO BLEED AIR OUT OF POWER STEERING PUMP.CHECK POWER STEERING PUMP HOSES.MAKE SURE.NONE ARE LEAKING OUT FLUID.

Have front tire's check out, but more then likely you have a bad front hub bearing. Have it taken to a repair shop where they can put it up on a lift and checked.

just check the wheel allainment

still sounds like bad tires to me.  is it an engine or belt noise?  Is it a whistle?

i would narrow it down to the steering rack or a CV joint
any noise comming from the front end like a clicking sound?