Is timing the issue with my Sebring?

I have a 2002 Chrysler Sebring. Recently, I had the water pump replaced. The shop I took it to, had it for 3 days, because they said they were having trouble getting the timing right. When I picked up the car, they said everything was fine, but its ran horrible every since. If Im driving it, the ride is nice and smooth. But when I start it, the engine acts as if it wants to die, and does the same if I stop at any time. The codes Im getting at auto shops are saying that the system is running too rich? Please help me, could this be the timing?