That lemon ruling only applies if you purchased this car brand new, not if you purchased a used car.
Did you get the car from a private party,,or did you buy it at a pontiac dealer ?
If you bought it from a private party,,then you are on your own and all the repairs will be out of pocket.
If you bought it from a dealer, you must of got some type of warranty, and if it keeps having the same issue, then that will be documented.
If the dealer can't fix it, then it will be the dealers responsibility to find some one who can.
A car that shuts off while driving is a safety issue.
Contact your state dept. of consumer affairs,,better buisness bureau,,bureau of automotive repair,,etc