I have managed to get RMS component stresses out with: STRESS(SORT1,PLOT,PHASE,CORNER,PSDF,NOPRINT), although not VonMises. I use FEMAP 2019.1 for post-processing, if that helps.
Nastran does not calculate the VM stress PSDF response. MSC Patran Random tool will allow you to do that. But in that case you are running random outside of nastran.
If you already have an input PSD for Nastran (TABRND), along with the RANDPS entry, then you can put those in thier own file and then MSC.Random can point directly to that external file. There should be an example in the Random docs...
