Nickel and diming

Just gonna mention "Intake manifold valley pan gasket" because it's not on your list of fixes and those are kind of a "when, not if" problem...

I know when the coil went out in my Jeep it started cutting out around that speed usually during a steady cruise (light load), however that's a 1993 with the OBD1 system, I don't have experience with the later OBD2 JTEC system like in your Ram.