95 Caprice Classic Engine Dies 2

It use to run awhile then shut off. Now it cranks once in awhile for a few seconds. Has new fuel pump and pressure,dist,module and coil. It has no fire from the coil. Someone told me you have to have the ecm or pcm programmed at the dealer. I was wondering if this is true. I've tried unhooking the battery and unplugging the o-sensors. Any suggestions.