I used to deal with that kind of thing all the time. Have you checked the actuall control arm? The axle hubs at the wheels? The actual spindle it self? The pitman arm? The whole tie rod itself? Check the steering gear too because it might have some slack in it that causes the tires to misalign, The friction from the road tries to push the tires back making them want to pull in opposite directions. Try driving it in reverse to see if it still pulls. Also check to see if a brake caliper has locked up or is wont retract all the way back into the caliper. That happens alot especially on 4wds mainly dodges. These are just some of the things that one might not think to inspect. All of these things have caused me head aches in the past with problem 4wds. I had one where he ripped the frame where the steering box mounts. If he broke a tie rod he probably turned when he shouldnt have like in deep ass mud or caught a root in the mud. The main things are the brake calipers, steering gear, or the hub and spindle unit. If i had to guess its either the tie rod is bent or the brakes. However you should try rotating the tires first.