My 1993 3.8 has an ignition module. ONce dead, that was it: not intermittent. Totally different from your 3.1 that uses a rotating distributor.
The other issue was the ignition switch itself. Started as an intermittent problem..but got worse with time. It is acted on via a long metal link that goes to the ignition key barrel. It is located low on the steering colums and almost out of reach. I have simply added a relay that I turn ON with a separate toggle switch . This relay applies 12V to the fuel pump circuit (common to the ignition circuit). I still need the key to start but the engine, once started, is kept alive by this circuit. But again this is for the 3.8.