cold idle problems

[TheSparo]

when i start my car when it's cold, it will start fine, and go to 1200, then half a sec later, it will stumble and die, it would do this until i manually kept the idle up until it was warm, The car idles great when warm, no problems with that. Any ideas? timing is good on it. Also, i was thinking maybe the Coolant temp sensor? or is that a different problem?thanks