My 2004 Jetta randomly shuts off while stopped.

I need help to figure out why my 2004 jetta shuts off randomly. When it shuts off, it usually stops when im idling. But its becoming a serious problem, when you are sitting in a intersecting. But its a manual 2.0 litter, gas. It first started out, it having a hard time starting when it rained, so we thought the coil pack could have crack and water was seeping through it. So we replaced that, and this new problem happens. It just stops randomly. Any suggestions?