Here's the story -

94 z28 runs fine - randomly stumbles & dies - will not restart (by ignition or popping the clutch while coasting).
Will easily restart with starting fluid sprayed in the throttle body & then clears out and runs fine again.
Pattern repeats about once every 15-30 mins

No codes.
Fuel filter changed.
Fuel pressure constant at 40-41 psi (even during/after stalling episode).
No dependence on temperature or rpm before stalling.

Question seems to be what could cause the injectors to shut down, but then refire fine when the engine is cranked with starting fluid? Any signal to the PCM that could do this? One of the opti signals?

Any help/suggestions appreciated - before my car gets rammed in the back in Houston traffic!