Here's a video, which also explains about measuring resistance when cold:

http://www.youtube.com/watch?v=uRcgdo4tfFo

A slow reacting coolant temperature sensor may possibly cause problems too.

 

Coolant temp, intake air temp, O2 sensor are all monitored by engine computer which can be accessed w/ an OBD2 scanner. If you know someone w/ a scanner that will monitor system sensors, this may allow you to check several things at one time.

The OBD2 scanner will also report fuel trim which may also indicate a problem. Most of the key components will set a CEL when things are not w/i specification. So your problem is something slightly off, but not enough to set CeL. This makes for a difficult problem to resolve.

good luck