Dennis,
I'm no expert here, but I sat and tried to figure this one through in my head and end up in the same place as George, cam timing out of sync. for some reason (cam to sprocket pin sheared?)
You have low compression on all cylinders, poor vacuum and the problem worsens when the engine warms up. Can you pull a rocker cover and loosen off a pair of rockers, see if the compression test jumps up on that cylinder. I suppose you are going to have to pull the engine to get to the timing cover anyway?
Good luck
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.