Park car and leave. Come back few hours later and it will not start. Engine will not even turn over. Not battery. Cannot find anything wrong. After leaving overnight it will start up perfect and run a few weeks and it happens again. Mechanic can not find anything wrong with car or system or battery.
Could be an intermittent problem with the neutral safety switch.
Yes, or ignition switch. A different mechanic may have more interest and ability to investigate this problem, or show you what you can check for when it occurs. Expect to pay for that advice - it is worth something if you want a reliable car.
I second looking around at different mechanics. Some mechanics absolutely loath electrical issues and will try to write you off because they dont feel it’s worth it. Some really arent skilled in electrical work and really don’t know what they are looking for. Intermittent problems can be especally painful to track down because you have to try to recreate the no start condition and that can take days upon days. No offence to veteran mechanics but with today’s cars having more and more complex circuit integration many older gearheads just dont know what they are looking at.