Steve,
With all the fresh parts and wires you've tried, I would look at anything your have NOT changed yet. The distributor pick up is a good suspect, especially if you have vacuum advance. The pick up wires flex as the vacuum advance moves it. The copper wire can work harden and crack, while the insulation looks OK. I had a duraspark fail that way, and it was a bear to find. In fact, that is the only failure I've ever had on a duraspark.
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.