Dart dies when hot???

The shop thinks the coil is the problem too. The coil was part of an old Accell 300+ ignition I had in there. I was having problems starting/ running and I swapped the box for the MSD but left the coil. It worked much better with the MSD box until today although I really only drove it once. Coil is Accell #140019, intended for CDI I believe. Probably won't to replace it.