Idle Issue

[n2hunters]

Since this is my very first post, I hope I am putting in in the correct section! Please don't be too judgemental.

A few months ago, the idle was intermittingly rough and would do a slight surge at a stop light. When that would happen the RPMs would go up and then back down. We replaced the ICP and it ran great with no issues for a month.
Now upon cold starts, the truck idles rough. After a longer drive, it does smooth out. So far there are no performance issues, but the rough idle went from slight to far worse and it taking longer and longer to smooth out.
There is no black or white smoke, no oils leaks, fuel leaks, no codes that come up, and the check engine light has not come on once.

Any ideas of what is going on?

BTW….the FICM was recently repaired by FICMrepair.com so I know that cannot be an issue either.

[04cr450]

You should check the ficm anyways, just for a piece of mine.. I would get your injectors tested. I had a rough idle all the way up to around 1200 rpm when cold and i lost an injector. Did you replace the pigtail when you replaced the icp?

[n2hunters]

I agree, we should check the FICM just in case. I don't think it is the issue, but you're right, I would rather have piece of mind.
We did not change the pigtail when we changed the ICP. Could that cause this idle issue?

[04cr450]

Yes the pigtail is the big reason for the icp going bad.. Change the pigtail for piece of mind as well