si90rex

B18a starts and idles shudders and stumbles for about a 30secs. It sounds like it's missing, rev it up (4000rpm) a few times and it cleans up, then Idles fine. It puffs smoke out exhaust (only during the start up idle issue) which varys, some days it's barely visable, other time a large puff visable for the rear view mirror. Once the miss fire is gone, runs as it should. But follows a heavy fuel smell. It's grey/white in color, but I don't seam to be loosing oil, or coolant. I just changed the oil (yesterday), it had no coolant in it. The coolant isn't pressurized when the cap is removed once it cools. The car doesn't over heat. The plugs show no sign on oil residue, the top of the piston does look glossy black. It's idles seems to stumble longer if the car is started with the ac on. The problem started like a month ago here and there now it's every time I start the car. I have tried pulling the plugs one at a time to isolate the problem, but i really didnt notice a cyclinder that had no effect on. Any help would be awesome.