Hey y’all this is my first post I have a 99 Xj it has 306k on it it runs great down the highway but about 2 min or so after you start it it will start to stumble and try to backfire then will clear out and run fine if it’s left to idle very long it will start stumbling and rough idling and stall out I’ve ran my scanner on it and got the P1391 intermittent crank and cam sensor failure and an occasional O2 sensor code both O2 sensors are new tho other strange thing I found was my fuel pressure would dip from 32#ish at idle to 10# just before the issues would start and would return to 32# and it would run fine thank you in advance for any suggestions

 

Crank Position Sensor (CPS) is the prime candidate for "intermittent stumble and stall" issues. Since you're getting the code, you should replace it, with a Mopar if possible... Fix that and then see what's up with the other issues...

 

^^
And next: check fuel pressure with gauge
What brand O2 sensors? NGK is the go.