It could be a sticky IPR. Not really any tests that you can run on it. You can remove the solenoid and check the resistance. Usually around 10 ohms is what I remember seeing on the solenoid. Other than that you can remove it and rebuild it with the instructions available online.

Have you also checked the ICP sensor? Make sure it doesn't have any oil in the connector.

Hooking the truck up to a scanner that can read the ICP and IPR DC when it is cold is what you most likely should do. That will give you a better idea as to why it is rough on cold starts. Also try switching over to synthetic oil. Most claim it helps cold starts a ton.

 

I had similar problems with my e99. I had it towed home twice. Took it to the dealer once and had it towed home from there as we could not agree on repairs.

I fought with it for months and finally changed all the injectors and the IDM as well as doing many other mods recommended in this forum.

I seem to have fixed it but still have my fingers crossed as I have not put many miles on it yet.

I also bought an AE and am learning what the codes mean.

It has 190k miles on it and the injectors looked like they were original with the old style black O rings. Compression is good.

It was such a great running truck until I got a load of bad fuel with dirt and water in it.

 

Solution was the ICP Sensor. I did the trick of removing the connection while running rough and it purred like a kitten. Changed Sensor. Runs Great. Thanks to the Forum.
Happy New Year.

 

Same problem I'm having...

I somehow had two ICP sensors, swapped one for the other and it still has a somewhat irratic idle, but it's much more stable. Need to call up Clay and get another ICP though.