2000 Pontiac Grand Prix My car is jerking and cutting off!

Engine Performance problem
2000 Pontiac Grand Prix 6 cyl Automatic 201404 miles

Hi, I have a 2000 pontiac grand prix V6-3.8L.
My car does not make any other nosies only ones related to it jerking. Most of the the time you can't tell that my car is even running because it is so quiet. I also have never had any other problems with my car.

My grand prix's check engine light came on and it eventually started jerking and sounding as if it would cut off. It would do most of the jerking when I would drive slow or stopped at a light. It almost sounded as if the gas was not getting through to keep my car running.

Eventually it cut off on me, but it would always crank back up. And it always cut off on me when I was still or idle never when I was driving. I took it to 2 mechanics and put it on two different machines and they both said that it was the catayltic converter and air sensors. So I had them replace wat the machine said was wrong. The day after I got my car back it started doing the same exact thing it did before they supposedly fixed it. Please help me!