NEED HELP
 

I have a 2003 6.6 diesel I have been having a issue with it just shutting off at red lights and not cranking back up for about 1 hour. I put a lift pump on it and installed a new cat filter with there adapter. it run great for about two weeks then today it started doing the same thing it would crank and start surging then idle out but when I put it in gear it shuts off and will just spin over.

the pump is working and its getting plenty of fuel to the filter

thanks for any help