Starting Issue

1996 Lumina starts. Or not,
when it doesn't start, there is no clicking, ticking, etc.
The fuel pump does engage, all dash lights, etc. Work.
Have replaced starter, solenoid, ignition switch.
Have checked all fuses, tested all wiring for power under the hood and under the steering column.
Have checked and replaced the relays in both fuse boxes that are located under the hood.
It may start 4 or 5 times, then nothing for 10 to 15 minutes of trying.
Started doing this last Thursday and is getting worse. Do not want to be stranded.
If you have suggestions on what to check or replace.