Fuel Delivery problems of the 2003 BMW 325

There is a problem with the electronic throttle/engine management control module. Whenever accelerating from a stop, the car lunges forward, then stops and goes into a cycle where it does this "bucking" action a few times. The car is 2 years old, but has only done this for the past year. I've attempted to have this repaired by BMW- have been working with them for the last eight (8) months with no result. My family refuses to ride in the car because the jerking motion makes them sick. A BMW field representative knows about the problem but refused to diagnose or repair the problem. I hired an independent mechanic that was able to trace the problem to the electronic throttle control, but does not possess the BMW software or equipment to repair it. Now it has become more and more dangerous to drive because the problem is getting progressively worse. It's is difficult to make left turns at intersections since the car jerks forward and stops. A few times I was almost hit by oncoming traffic due to this.