2003 Dodge Neon

Engine Performance problem
2003 Dodge Neon 4 cyl Front Wheel Drive Automatic 107000 miles

The engine " misses a beat" when idling and runs rough when backing up. The only real problems I've
noticed are water flowing out of the muffler (not the tail pipe) which seems to indicate a hole in the seam. And, there is a strange " dead fish smell" coming through the vents. Any suggestions?
April 24, 2008.

Water leaking is normal and its not an issue

do you have check engine light on
check for codes
switch your gas brand

Apr 26, 2008.