[1997F350bully]

Hey everyone,
I have a 2001 F-550 7.3 Powerstroke stake body, and recently the truck started idling bad when cold, but after up to normal operating temps it clears up. Now when I start in morning 35 to 40 degrees, it idles rough, sounds like a miss, wont rev up right like missing and no power. But drive down the road and when the temperature reaches normal levels it the problem just vanishes like someone switched the problem off. Runs great after that. It is showing a service engine light when problem is occuring,but like said the temp comes up the light goes out and the truck runs great. Try to hook up OBD2 reader and the reader does even come on, but it works on all other cars so its not the reader. Please help!
Thanks, Brian