Hi prutter,
When the car smokes black that means it is flooded with fuel or running rich. Since the problem seems to occur with temperature you may have a bad coolant temp sensor. I would replace it and see if it helps. Make sure that you replace the one that has two wires and is for the computer. If the car is hard to start try depressing the gas pedal all the way down while starting this will help to lean the rich mixture.
ASE Certified Technician
Master ase technician, Maryland state inspector