cg6521

My co-worker noticed that in the morning when I start my 1994 ES300, that there is a small buff of dark smoke but it is not there long enough for myself to get out of the car and check. It seems to be on the intial start-up because later in the day I had my wife start it up and no dark smoke. What could be causing the dark smoke first thing after it sits for a few hours? Thanks.