Car Hesitates while stepping on gas and turns off randomly

So I took my Saturn in for a routine Fluid change. Local Shop was running a special where they replace all your car fluids. While there I told them my car would randomly shut off some times. It would start right back up but this problem is very dangerous and annoying. So I left it there and they "fixed" the problem. They changed all my fluids and replaced all my spark plugs and wires, PCV valve. After picking up my car I noticed it started to hesitate while giving it gas. I did not have this problem before I dropped it off. I called the shop and they told me it was the cleaning fluid they put in the car and the problem will go away in a day or so. The next night the car shut off again. So I called the shop and brought it back. They had it for 3 days. They replaced the fuel filter, checked all their previous work ran all the tests on the car and the car still shuts off and hesitstes while first giving it gas. Does anyone have any ideas as to what might be the problem because no one at the shop seems to know hwat it could be