I have a 2002 chevy 1500 with the 5.3 when cold weather below about 32deg, when starting cold in the morning especially, the idle will be eratic and the engine stumbles like it's missing on a cylinder. The engine will usually die and hard to start back up. When it warms up slightly to about the first mark on the temp gauge, the service light goes off and the engine runs fine. No code is stored on several checks with code reader. During warm weather I have no issues at all! I've put a new IAC on with no results still have the same problem. Would anyone happen to know what might be going on here? Thanks for any help.