Possibly: dirty fuel filter, dirty air cleaner, incorrect fuel mixture screw setting, carb needs rebuild, if it never ran with that carb could need re jetting, weak coil, bad motor ground? Just a few things I would check out.
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.