98 Sable GS

Have a '98 Sable that is very unpredictable, car runs good, but fails to start sometimes, very intermittent, seems to be getting gas sometimes and ignition, just not starting. Other times it just fails to start, doesn't seem to be trying to. Have had it in the shop, of course it started everytime for the mechanic, couldn't determine the problem. usually will start after sitting an hour or so however. Any help would be greatly appreciated

It really sounds fuel pressure related.