I have a 2003 chevy 2500 with a 6.0. It just started cutting out and now the A/C is not working. We have replaced spark plugs, wires, MAF, air filter, and its still missing. It starts right up and doesn't die, but idles roughly. Idk if the a/c has anything to do with the rest of it, but it has me stumped. I dont want to go and replace the expensive and hard to get to fuel pump until i can make sure its not something else. Any suggestions?

 

Take it to your closest Autozone or Advance and have them read the engine codes for you. It could be anything from bad plugs to an O2 sensor or clogged catalytic converter. Not enough details for anyone to give you a definite answer.