Magnum swap starts, does not run

When I first did my manual trans magnum swap in my Dakota, I had an auto PCM in it, it ran fine but threw auto trans codes, so I don't think that is your problem, but not sure. Also double check the PCM pinout and make sure there isn't a 12v ign source missing. It almost sounds like an old ballast resistor issue where it would run in crank but die in run?