Cold morning idle

[BoomInTheTrunk]

when i start my car in the morning the engine seems to vibrate alot. I turn up the idle control knob until the engine is warmed up so it won't vibrate. it only seems to vibrate like that when cold and under 1000RPM. once warmed up the car idles just fine. my question is what could cause this. The valves were adjusted about 200 miles ago and the motor mounts seem to look in good condition.