I had the same problem with my car about a year ago after it died on me. Your car's symptoms sounded exactly like what I had, but unfortunately I have to tell you that with that kind of problem there are many possiblilities. With the sputtering and hesitation of the engine it could be one of many through my knowledge of experience. First of all start with the less inexpensive issues like spark plugs & wires, rotors & caps, or check if there's water in your gas tank, you can eliminate it with the tank cleaners you see at auto shops. It could also be your trac switches...there's 2 under your hood, they're easy to locate, almost in the center, and like one of the other members has mention check your gaskets. Well that's all I can tell ya, but the solution to my problem was a new trac switch and professional tuning did the job. Good Luck!!