Thanks for the replies.
Yes, the trap oxidizer has been removed.
Once the 'problem' starts then the smoke is thick and black. The last time it happened, after I let the car sit for 30 minutes, I turned the front defroster on to draw the heat off the engine and it ran a better (faint smoke and ok acceleration) until I got home. To state the obvious: it seems that when something??? gets warm then it doesn't work correctly and after it cools down then it is ok.
And now, while the car starts, the glow plug light no longer comes on. Bother!

Thank you.