IPC Replaced - now have check engine light

[lovethydiesel]

I just replaced the IPC sensor on my 2003 E350. It had 290,000 miles on it and it was the original. I did it because my idle will slowly get faster and faster. A quick kick of the accelerator and it goes back to normal, but then it will slowly take off again.
It was not too bad a job. You definately have to get the intake hose out of there. An 8mm on a swivil joint connected to this special tight access palm ratchet from Harbor Freight did the trick. Then you have to use a 5/8 crows foot on a wobble extension to unscrew the old sensor out.
Does anybody want to speak to putting the new one in? There is an o-ring at the base of the sensor's threads. I put a little oil on this and screwed the new one in tight with a 3/4 inch stubby wrench. Then connected the wires back up. I had to pull the wire connector a bit to make it reach since the orientation was 180 degrees turned from the original sensor.
Here is the sucky part. When I buttoned it back up the check engine light came on and the idle problem wasn't fixed. I feel like I just spent $80 to turn on my check engine light. Would something I did cause the check engine light to come on? Is there a way to turn it off without paying someone with a scanner to do it? How about that idle problem, any ideas? Thanks!

[jesilvas]

The idle 'problem' sounds almost normal.
Does it do it when cold? Because the OEM programming is to increase idle speed to help warm up the engine.

[lovethydiesel]

It will do it even when the engine is at operating temperature. However, when you say cold, do you mean cold outside? Perhaps there is an intake sensor that is sensitive to cold temperatures and raises the idle. I wish I had a tach to monitor it better.