2006 Jeep Wrangler Car sways while driving

I've recently been to the Jeep dealership 3 times without any success in fixing my problem. I'm not sure how to explain my problem. While driving my car on the highway, the car seems to sway either left or right. Its a weird floaty feeling. It almost feels like I'm driving the jeep on an extremely windy day, everyday! I brought it to the dealership and they replaced the Intermediary steering shaft. That didn't work. Then they replaced the stabilizer (or stability bar). That didn't work either. I brought it a third time and told them to take a look at the tie rods, they supposedly did an entire diagnostic. What that means, I don't know. They told me they found nothing wrong with the car. Now what? I'm terrified to drive my car as I drive 64 miles one way to work. I feel like I may lose control of the car and may kill myself or someone else. Also, the first thing I did was buy new tires, balanced and rotated aswell as aligned them.
Please Help!