I had the same problem with my Olds. Tried all kinds of blankets, insulators,
new battery, new battery wires, connectors and who knows what else through the years. Finally put a Ford solenoid in the system and haven't had a problem since! MAD makes a handy kit with everything you need. but you don't really need the kit to make the swap.
http://www.madelectrical.com/catalog/st-1.shtml