Sounds like a "Bump-steer" issue to me.....http://dazed.home.bresnan.net/bump

 

When you jack it up, are you lifting the front by the crossmember (unloads the suspension) or the lower control arm? Lift it under the arm and then check the wheels for play. It does sound like bumpsteer and wider tires will amplify bumpsteer. They also cause the car to track the ruts in the road more than a narrower tire will.

 

Oh crap, double post!

 

I posted this awhile back. I think I traced my issue to the steering box. Tightened the adjuster screw all the way down and it seemed to fix it. If I ever get the car on the road for good then I'll know for sure. I had everything aligned and checked and all the suspension components look good. And no I haven't done the shelby drop or nothing. It's completely stock at the moment (possibly original ha). I do plan on suspension upgrades in the near future though.