2000 Saturn SL2 engine dies often but can be restarted

My Saturn engine dies more and more often. It happened starting around one year ago when I waited for a traffic light. I had to restart it. And then,
the engine dies more and more often. Usually, it happened when I made a turn and waited for a traffic light. These days, even during driving on highway normally, the engine died sometimes. However, I can always succeed in restarting the car (sometimes I had to turn the key several times).
A mechanic checked my car, replace the four starter plugs and fuel filter. The problem wasn't fixed. I knew that catalytic converter of my car was also broken. The mechanic told me it could be the problem of "catalytic converter". But I am wondering "catalytic converter" can cause engine die during driving.
I do greatly appreciate for any advices or possible solutions to this problem.
Thank you very much in advance.
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<snip>
If there were a "Saturn FAQ," this would be one of the top few entries. If you do a Google groups search (http://groups.google.com /) against this newsgroup (rec.auto.makers.saturn), you'll find many, many articles dealing with engines dying and/or revving low. IIRC, Coolant Temperature Sensor and fuel problems (for example bad gas, bad fuel pump) can cause these symptoms. Hopefully, others with better memory and/ or more experience than I will happen along and provide more useful information. Good luck!
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Well, it seems to me there are many possible cases. I will try some in this weekend and let you know how's going.
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I'm coming back to report the result. I fixed the problem which was caused by EGR valve failure. I tried to clean it but after a while, it failed again so at last I bought a new one and then everything was perfect.
Thank everyone here. I got many useful advices.
Good luck.
-- Message posted using http://www.talkaboutautos.com/group/rec.autos.makers.saturn / More information at http://www.talkaboutautos.com/faq.html
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