I'm assuming ignition means ignition control module.
What does the fuel pressure do as it shuts off / when it shuts off?
Time to take it to a shop or dealer that has the tech 2 scan tool so they can analyze it and see exactly what is happening.
96 T/A, Black/Graphite Leather, T-Tops, 6 speed, 10 speaker Delco/Bose "Monsoon"
Original owner, 192k miles and counting.
Total engine rebuild at 187,020 miles. AIR delete, bored .030 over.
Comp cams Xtreme Energy LT1 266HR-14 street cam and springs.
Custom leather interior at 189k miles