2005 Rolling Idle at cold start only

[neil]

I've not driven my truck much lately because I've been working alot and have a company truck. So once a week is probably the norm...if not two weeks. Just wanted to put that out there if it helps diagnose.

I have noticed that cranking times seem slightly longer that it was over the last year. Yet, sometimes it cranks and fires quickly. Time sitting seems to have no part in this. It's random as to how long it cranks. But it's definately not always the same.

The last two times I've driven my truck, I noticed that it cranked a little long...but once running, and after idling for about a minute...the rpms seem to start wandering up and down, or hunting for a stable place. It's not rough as far as the engine running, but the rpms are clearly dropping then picking up. Maybe 100-200 rpm up and down. It will stabilize to normal, then do it again.

I held my foot on the pedal to try and hold say, 1200 or so, and it would roll or hunt at that rpm too. I couldn't hold it steady. Then once it warms up a little it gets better. When I'm up to temp it's completely gone.

Any guesses based on this explanation? ICP, FICM, Batteries? I checked voltage of batteries during this event and they read a nice 14.5 +/-...assuming thats normal.

PS: Fuel filters were changed 7K ago (motorcraft) and my fuel is from a consistent clean source that I've used for years. Engine has Rotella T6 and Stanadyne in fuel. I've ran Stanadyne about every 3rd fill up for a year now.

[neil]

Any guesses on a wandering idle startup/warmup...when coolant temps are cold only? I want to address this as soon as possible to avoid other items (like injectors) from suffering. Thanks in advance!