I had a CIS injected car do this years ago. It turned out to be an injector leak. They leaked gas into the cylinders which flooded the engine. When the engine cooled, most of the vapors evaporated and the engine liked the rich mixture when it was cold. Only way I know to test for this is to remove the injector and power up the system with the engine off. Unless the injector is being addressed to fire, it should be dry.
Other thing is vapor lock due to low fuel pressure in the lines under the hood.
