my 1984 300td has a hard time starting cold. I check the glow plugs they are good and they get 12volts when i turn on the key. Some times it takes 10 tries before it turns on a lot of white ish smoke comes out and if i drive it cold it has very low power and lots of smoke, until the car gets warm and from then on there is no problem restarting or power. what should I check next? thanks