With so little info to go on, there's a few things it could be: It could be that your ball joints or the hub bearings are going bad. Jack the front of the truck up, make sure it's properly supported, and spin the each of the front wheels. Do you hear anything or feel any "grittyness" to either of them? If so, then it's your hub. If not then have someone else turn the steering wheel for you while you listen and look at each ball joint. If the rubber on them looks compromised, you'll need to replace them. If they have grease leaking out - again, recommend you replace them. Check the front sway bar and the ends of the rods on it. Give it a few good tugs (make sure you stay out from under the truck and that the truck is 100% properly supported so it won't fall off the jacks - I always jack mine up, put two jack-stands under, lower it onto the jack stands, and then, for extra safety, move the jack to center line and put just enough pressure on the frame to give extra support. - oh, and also chock a rear tire in front and behind it.)