Ballast resistors suck and are the source of many start/run problems. Do as MSD says and get rid of that thing. I put the exact same "system" on my '69 340 and it made a huge difference, especially with hot starts.
Thanks. Did you follow their instructions exactly? That is, did you just take the ballast resistor out and connect the wires together; and did you connect the original coil + wire to their light weight red wire?
