Hi kelly:
First I would check the valve adjustment if it hasn't been done within the past 10K miles and then I would add Redline to your fuel tank. A whole bottle with the first tank and then half a bottle with the next few tanks. If you can;t find Redline then the Diesel purge will do, but run it straight thru a clean (new) fuel filter. (it's easy to do.)
I've got a silver-blue 300TD that i've babied since new and it NEVER smoke, (until i forget to check the valves, about every 20K is OK) I have always used redline and to date I burn ZERO oil and virtually no smoke.

good luck,