Breaking up

Hello ,I have 340 ralley Challenger,now it has 440 4spd usded stock Elc ignition for a 73 car my problem is car runs poorly ,feels like ignition problem everything is new motor is 1976 rebuilt , Iwas checking voltage from battery to ballast resistor only have 10 .4 volts ,wondering if it needs a full 12 , also swapped out control box car still acts the same . car also doesn't run Well with no load while driving ,if your on the gas it will stay running , but it feels like it's struggling to run ,like it's breaking up ,Vacume is around 10 pulls up to 15 to 18 when you rev it , I also changed the Distributor cap , thought maybe it had hair line crack. Any ideas ???thanks Gregg
Author: Gregg123