You stated that the fuel pressure is correct. What was the reading & how long will it hold pressure with the key off?
You can check fuel injector pulse with a #194 automotive light bulb. Disconnect the wires going to a fuel injector, straighten the wires from the base of the bulb & insert into the injector harness. Watch the bulb & see if it pulses while someone cranks the engine.
Please make sure the fuel pressure is holding before checking for fuel injector pulse. It'* possible for the upper intake manifold to explode if fuel is leaking past the fuel pressure regulator. Your description of internal explosions is making me nervous. You should also check for fuel in the vacuum line going to the fuel pressure regulator.
1999 Pontiac Bonneville SSEi (son'*)
1997 Chevy Lumina (daughter'*)
2006 Chevy Trailblazer (wife'*)
2006 Chevy Monte Carlo SS (Mine! -Zoom Zoom Zoom)