Crysler Lebaron Stalling Question

1991 Chrysler Le Baron: v6: 100,000 miles

Hello: I recently had a friend replace my water pump & when I picked up my car, I noticed that it was idelling poorly. At first, it would die every time I stopped at a stop light, got off the highway or hit the brake. I replaced the battery b/c I read on-line that this could be an issue, and it helped. However, the car still dies at stop lights and is not running like it did before. If I put the car in neutral, then it won't die at stop lights. I was wondering if you had any idea what is wrong with it? I'm 99% sure that he did something when he was repairing it b/c he had a very hard time with the repair.

Thanks so much for you time :)