oscillating revs

we have just got a 96 civic vti and when its cold the revs go up and down. it doesnt do it when its idling only when driving and it worst between 2-3000 rpm. I was told it was the automatic choke but the mechanic says he cant adjust that any further. We have tried injector clean and a higher grade fuel but still does it. Once the car temp is up to normal it seem to stop. Another mechanic told us it was an electrical fault as the econmy light comes on as driving, but i thought that was normal. Can some shed some light on it before i go to a third mechanic

read this

http://www.automotiveforums.com/vbulletin/showthread.php?t=468015

It's because your fast idle valve has backed all the way out and gotten stuck. Take it off from underneath the throttle body, take it apart and twist the screw all the way out. Put it back on and it will be good as new.