Sig you have a Holley so I doubt you will have problems with the float bowls, and as accobra says you should just run one pump. Doug's setup is different and works well for him. I would run just the mechanical pump and remove the electric pump, it could be the electric pump is also wired off the ignition coil feed giving you other pains.
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.