92 lude problems

hey alright on my girlfriends 92 lude has a problem that when she stops at a light and then goes sometimes the car hesitates as if it is about to stall. The check engine light is coming on for a bad egr vavle, however the egr vavle has just been replaced and the problem is still there, the light is still on too. Also sometimes when turning the car off it will not restart for 10 minutes or so. I know there is an exhaust leak but i don't think that is related to the problem. Has anyone had this problem or are there any suggestions on what to do. In case anyone needs to know the car is an si and a automatic.