OP:
After the alignment's done and the tires are checked and other steering-related items are verified you may still have the same problem. I did and it was just as you've described. It turns a 300 mile day into a VERY uncomfortable exercise.
Although my 19.5" Goodyear tires appeared to be OK, they were almost 7 years old and I replaced them with Hankook's. The difference in handling and overall ride was gratifying ... but it didn't take care of all my issues.
After reading several posts regarding steering stabilizers I finally opted for SteerSafe's Steering Stabilizer. Their website is
HERE. This has made a world a difference for me and I am now able to relax enough so that driving it across the flatlands with semi's passing me is no longer an issue. Hitting crummy, pot-holed roads is also a lot less stressful. I feel very much in control. Installation is very straightforward and easily a one-person job.
From SteerSafe's website:
Steer Safe is installed on the vehicle’s front steering arms and clamps on to the front axle. No welding is required. It’s simply bolted on. Steer Safe Stabilizer’s patented oscillatable fulcrum bar makes it the only true steering stabilizer on the market. It provides up to 400 pounds of preset tension on each front wheel working against any outside forces, helping to keep the front wheels pointed straight, even in a blowout situation.
Unlike hydraulic shock absorber stabilizers that hook onto a vehicle’s tie rod, Steer Safe offers protection from the front wheels to the steering gear box. No extra steering effort is required lessening driver fatigue. Maintenance is not required because Steer Safe is equipped with Delrin bearings which never require servicing. If or When you need to throw some money at the problem, you might give SteerSafe or something similar a thought.