Steering Related Problems of the 2008 Ford Expedition

Steering problem

We purchased this 2008 Expedition last fall with the intension of towing a trailer across country because they came with high reviews and comfort. We first noticed the drifting when we picked up the trailer. The trailer fully loaded is about 6,200 pounds. We have a stabilizer hitch that we used to tow with. We took the SUV into a dealer to have it checked out. A mechanic suggested that they check the camber's. The dealer said all was fine. We took it on a 7,000 mile trip towing the trailer and immediately discovered that the towing ability was dangerous. The steering wheel was difficult to control. In all cases, no wind or with ever the slightest wind, the vehicle would drift from side to side and the trailer would wobble back and forth making it exhausting to steer. With high gusts it was almost impossible to steer even at 45 mph, it would drift from side to side making it extremely hard to control, and the trailer fish-tailing behind us. It was very dangerous. We could not go over 55-60 mph on a wind free day and feel anywhere safe. We took it into the same dealer when we got back home and they said that they didn't see anything wrong. We took it into another dealer and they also took it for a test drive and said they could not see any problems. There is something terribly wrong with this suspension and steering system and the dealers cannot put a finger on it. The steering wheel has a tendency to cause the SUV to drift while driving even without the trailer. It feels loose. It also at times, has a knock in it like something is either snapping back in or snapping out of position. We are at a loss and don't know where to turn for help. We love this SUV other than these driving problems that are dangerous.