Electric Power Assist Steering System problems of the 2002 Cadillac Escalade

I am currently having a re-occuring problem with the stability track. I have had it serviced four times now to no avail. Each time I take it in they tell me it is a computer problem, and that it just need to be reset. I have yet to have an accident, but today I almost did. While going to the curb entering the freeway the steering went crazy and the service stability track notice appeared. After I entered the highway the vehicle still was jerking uncontrolable. I turned of the stability trac button in hopes of gaining control. The vehicle still noted the problem even after being turned off. I again have taken to the dealership in woodland who stated it had to be my 22" wheels. But, I find this highly unlikely since the dealership originally offered it to me upon buying and I had this problem three times before with the original 17' tires. I do maintain a record of all services and I have a copy of when I purchased the wheels, which was not until recently. This is the second Escalade from gm the first one was declared a lemon and this one appears to be turning out to be one also.