Classic symptoms of a vacuum leak. Probably needs intake manifold gaskets. The manifold cools down overnight and pulls away slightly, You start the engine and it draws in excess air giving you a high idle and rough. As it warms up the parts expand and start to seal back up and the engine runs better because it is now under computer control. These are common for leaks between the upper and lower intake manifold sections. The pictures show the o-rings and lower gaskets that fail. Normally I test both the upper and lower gaskets, It is not that much more work to do the lowers as you have the engine apart anyway.
Images (Click to enlarge)
Wednesday, May 31st, 2017 AT 3:35 PM