I think Laurence is on the right track, if it was a coil you would get a SES light, the alternator would not cause starting problems so that is off the table. I think you probably have a fuel pump going bad. It's rare to see a fuel pump not have catastrophic failure, but it does happen. Fuel pumps are designed to kill themselves if they start acting strange, they have a fusible link inside the motor and any strange behavior will cut the power to the pump so to avoid any possibility of electrical spark.

The first step is to confirm the fuel is getting to the engine and that requires removing the fuel line at the engine during a time that the engine wont start. There are safe ways to do this but they require tools I don’t think you have. The fuel pressure is not huge but it’s enough to be a problem if you do not have experience removing pressurized fuel lines. At that mileage changing the fuel pump AND FILTER would be a good start if you want to throw parts at the problem.