1999 Pontiac Grand Prix

Were any of those parts mentioned bad?

Did you change the fuel filter when you did the pump?

What is the fuel pressure when the symptoms happen?

What is common when the symptoms start?

This one can be a bugger, but here are my thoughts and some things to consider.

I assume this is the 3.8 engine, otherwise the fuel pressure is too high.

You'll need to do testing when the no start is happening.
Was the module tested when the failure was present?

When the no start is present, check for spark and for injector pulse. Check the wiring from the crank sensor to the ignition module. It might be chafing against the block or evap lines. Wiring can not only chaff but coolant, Oil, etc. Can break down the insulation under the tape. Pull them out of the tape and check them. Maybe when it dies you might be able to determine if the spark and injector pulse both fail then it might be in the crank sensor, module area. If injector pulse only fails, then it might steer you towards ecm. I know you replaced the crank sensor with a GM one and it is probably fine. All too often I have found the new parts do not always mean good parts.

Also, check ground connection underneath ign coil assy & ign connectors for loose connections. Check positive cable connection at the power distribution center to be clean & tight. Check ground connection below pdc.

I have run into Ignition switch intermittent issues on these.

Sometimes a Mass Air Flow sensor will also do this but it would usually show up in a tap/wiggle test. You can do this test with or wthout the symtom present.