My Grand Am acts like it is going to cut off. When you floor it, it decelerates like crazy then kicks off really hard. After that it works like a new car for a few minutes and then does it again.

My first suggestion would be a fuel issue. Might be water in the fuel.. try adding a bottle of injection cleaner during your next fill-up.. next step might be to have the fuel filter changed as well as a tune-up. Keep in mind, we only only go by what is written here. Without being able to see, hear, or "feel" what exactly is going on.. its tough to give an accurate solution. Worst case scenario.. have a certified mechanic diagnose the problem.