I have a 2013 ram w/ 5.7 hemi. We were driving and it just shut off on my wife at a stop light. She tried to fire it back up and when she tried it would run really rough and die. I got it home on a trailer and started messing with it. The only code i got was the po300 code. I've replaced spark plugs, checked battery voltage, changed air filter, cleaned pcv valve and pulled off throttle body and it looked ok. Anyone have any ideas what else would cause it to start up and die immediately unless i give it gas. When you get over 3000 rpms it seems to sound fine.

 

So, after you replaced all those things, it still does it? What as the battery voltage?

 

Yes after replacing all of that it still does it. Battery voltage stays at 14.5v when i can keep it running

 

I'd be inclined to suspect either the Crankshaft Position (CKP) sensor or the Camshaft Position (CMP) sensors are getting incorrect readings since the PCM apparently is not able to determine which cylinder or cylinders has/have a misfire. Does your scan tool have a datastream mode so you can monitor these signals?

-Rod