just to clarify : in my case the engines just lost power after gear up with AFE running the takeoff. That was a month ago or such. i had not used the DC-6 for a month prior to that.
PMDG support advised to delete and re-install as the MSFS Updates can reset some things in the installed airplane code or such. I am sure I said that wrong what they explained, but deleting (de-install in windows) and reinstalling the whole PMDG Operations center and then the aircraft in that PMDG program solved the issue.