Dunketh, thank you for helping.
Old ICV was disconnected.
Yes, disconnecting the new one makes car run better.
And cold start is getting worse with the new sensor.

Tabetha, thanks.
I have that car since 1999, and everything was fine until the ICV got stuck. Ford's racing mechanic told me not to bother and just disconnect it.
CO is 2%. Does the CTS activate the dashboard display, or is it a computer link only?