Jeep 2001 4.0L 6cyl

After I start up and drive my jeep around town and then shut the engin off. Then I get back inside the jeep, start it up the engin idels rough. Some times the engin light comes on. I had a coil pack installed and still the same symptoms. What do you think?

Sounds like a leaking fuel injector

Sounds like you should pull the codes when it throws a light