Re: Still have engine running problems
If you think it's fuel, try the "propane trick." It'll tell you right away - do a search. You might spend $10? max if you don't already have a propane torch and a hunk of hose.
If you suspect timing advance, disconnect the vacuum advance line and try it. Cost = 0. It must be PORTED vacuum.
Converting over from the MSD to HEI is just the cost of the module, a hunk of wire, and a couple of spade terminals -- $30?
Symptoms do sound like a defective coil wire though - you tried a different one?
MSD -- make sure the wires from the pick-up coil to the box are NOT running close to the high tension - coil wire, coil, plug wires. The magnetic induction will drive the box crazy! All sorts of problems.