Car starts then stalls

The key needs to be programmed to your car. Leave the key in the ignition the entire time, turn to ON, wait ten minutes, turn to OFF, wait five seconds, repeat that two more times. After the third time, turn the key back to on, and wait 15 seconds, and then start the engine.

This has already been posted on another one of your questions: http://my.cardone.com/techdocs/pt%2077-0011.pdf It is the relearn proceedure for all GM VTD systems .. Copy and paste the above link and choose your system.