GMC Repair: Message Center, fuel pressure, message center

Question
02 Sierra w/5.3 liter, 4WD, Automatic. Truck intermittently quits running at speed and at idle. Already replaced fuel pump and the relay and fuse but problem continues. This last time it happened the message center flashed 5(maybe 6) times. Any idea what else to check? And are there descriptions of the message center flashes

Answer
no descriptions of what the message center flashes are, does the check engine or service engine light come on?  if so that means it is setting a code, without knowing what code it is, there are many things to check.  Spark, fuel pressure, injectors, ignition componants, internal engine componants.  Did you use a GM fuel pump when you replaced it?