Replace everything from the steering box out. That should help. <img src="/forums/images/graemlins/zombie.gif" alt="" />

In my experience no one likes to screw with ifs tierods, and shops will let them go as "fine" as long as the grease boot isn't broken. Bad front wheel bearings can cause wobble also. Is it making noise any where or how?

FWIW, even only half-slick does a nice job of binding things up in 4wd and creates steering anomalies you won't have in 2wd. Once you get up on plane as it were, maintaining traction in 2wd is almost as easy as in 4wd by just putting weight in the bed and adjusting the throttle input at the pedal.