Air Bag Light On problems of the 1999 Audi A4

When the car was about a year old, the entire airbag system had to be replaced, the repair facility noted to me that I was lucky to bring it in when I did, as it was at risk for spontaneous deployment. Additional problems included an oil pump failure ($750) at about the three year mark; and occasional sudden lurching/rpm revving or sudden onset of a 'lag' in power, which the dealer noted when I brought it in but could do nothing about. I have also had problems with the fuel indicator gauge being grossly inaccurate - indicating I have used only a quarter tank of fuel to drive 350 miles. However, the most bothersome ongoing problem is four or five trips to the dealer to repair a non-functioning cruise control system. Each time they have 'replaced the vacuum hoses' but this 'repair' will begin to fail again later that same day. The system will either fail to engage altogether, or it will be engaged during highway driving, then within a few minutes, the speed will continually decrease until I have to manually disengage the system and turn it off. I reported this to Audi of America's corporate customer service (very friendly and helpful) who helped me arrange another service visit, but the problem has never been resolved. Cruise control has never worked and I'm giving up on it ever working. I just have to pretend that I don't have it, which is very annoying during highway travel.

Defective sun roof would open unexpectedly and not close. Dlr replaced sun roof. Also, speedometer malfunctioned and was not readng the speed accurately. Dealer replace speedometer sensor and gear. Finally, airbag light came on, indicating a problem with air bag. Dealer replace dthe airbag sensor. Please provide further information.