2002 xlt running rough

[paddler5000]

I have a 2002 xlt and it is running very rough at idle. My mech has changed the harmonic balancer and it is still doing it. Once the rpms are up it runs great. Any suggestions??
Thanks

 

[Curtis]

my fathers 02 had a similar problem, if you kept the RPM's up it would even out.

It turned out that one of the coils was bad. It had gotten wet.
We replace done, and all was good.
Then it happend again, and we sprayed WD40 on the coils and it fixed it.
it may be as easy as that.