It seems to be an electrical problem...

Here is an interesting read on Mopar ballast resistors.

http://www.tidewatermoparclub.com/TECH/ballast2.pdf

MSD Blaster coil is low impedence, so it does require a ballast resistor. MSD site has some interesting info as well.

http://www.msdignition.com/product.aspx?id=5003