Here for help

I didn't figure that this was the right place to post the issues. I will post a thread in the general section as soon as I'm off the road...in my rental

https://m.facebook.com/story.php?story_fbid=1087151508010688&id=100001475463734

The rpms started going crazy and then will drop to 0 and die. Sometimes it starts back up, sometimes it won't. Truck jumps just like the rpms do in the video so it's not just the gauges.

Code P0420 is thrown and I understand that is for the cat and o2 sensor but I don't know if one of those would cause the issues shown in the video and what to do from here

Cat was bad. Changed that out but during test drive it stalled. Started back up immediately and died after a short period of time. Did this repeatedly.

Now it just won't stay started, keeps stalling. Sometimes after10 min, some times immediately, sometimes after an hour, sometimes after 2min