When the car is completely cold (ie. overnight), the motor misses and blows smoke for about 20 seconds when started. It then evens out but sounds unhappy until warm. The problem only happens with the motor dead cold. Air temperature makes no difference. I recently changed the fuel filter, prefilter, airfilter, and did an oil change. The cold starting problem persists. I allow the preglow to do its thing, as I always have. The motor always fires immediately. This problem started all of a sudden, without warning. Any ideas?