Car staggers on acceleration intermittently.

My 1998 Cavalier staggers on acceleration intermittently. It will also kill on occasion when the clutch is depressed & I'm slowing down to make a turn. When the problem 1st appeared & the check engine light came on the diagnostics read "Low exhaust gas recirculation". I was instructed to replace the EGR valve, which I replaced, but with a used one. I also cleaned the idle air control valve & replaced the oxygen sensor. I have also used JB injector cleaner. What else should I check? Is there another sensor that can cause this problem? Could it be the catalytic converter? How do I check for a bad converter? Is there an easy way to check the EGR valve to see if the used one I put in is working properly?
Any help would be greatly appeciated.
Thanx,
Steve
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I'm having that same problem.
Somebody , if this problem is familier to you and you know the answer please, ...Help