My Tahoe has a 4" Rancho lift and 33" BFG MT's. I had them balanced already and aligned but still have shimmy. It only happens aroun 45mph and stop above 50mph. What could be the problem?:confused:

Do a search for "death wobble"... you should pull up a lot of posts on this.

It can be caused by a lot of stuff (I'm not sure on new IFS stuff though that's all a mystery to me on what's down there)... I'd check every single bolt/nut and tie rod end on the front suspension. See if anything is old and worn out or loose. Even if you have had the tires aligned you can still get it based on the toe in/out factor. The steering box mount flexing can do it, a lack of steering stablizer, spring bushings, bearings, a seperated belt in a tire, caster.... that was the list I was given when I had the wobble. Turned out to be loose parts... hope it's something simple like that for you. Good luck.....

Grab the flanges that your half shafts bolt to and try to move them up and down. If you have more than 16th of an inch movement in them, you need to replace them. It's fairly common to have them go out from what I hear on the S10 boards.