Since you say you've "tried everthing else" let me tell you a tale about front end alignment. When we bought our rig, I felt the steering was somewhat vague, and asked the dealer to check the alignment. They said they did, and it was correct. At the time I felt they were just telling me what they thought I wanted to hear, and doubted they had done anything.
Still not satisfied after adjusting tire pressures and some seat time, I took it to an independent shop for tire truing and asked them to align it. They trued the tires and told me they checked the alignment and it was fine, so they did not charge anything for the alignment. Hmmm... no charge at all to measure it? I figured they just did not really want the work.
Finally I took it to a shop which specializes in suspension work for commercial trucks class 8 etc. They did it right; placed shims between the axle and springs to adjust the caster, set the toe, recentered the steering wheel. A great improvement in steering responsiveness was the result and it got rid of the vague wandering at dead center.
This is why I hate having work done. Too many shops just want to take shortcuts.