Q&A

The only way to figure out why your car is intermittently failing to start is to get the car to fail, and then have a friend crank over the engine and test to see if you have spark at the spark plug wire, (that would indicate the ignition system is OK), then crack open the fuel line at the fuel rail and see if on cranking the engine is receiving fuel. If you can determine this and know the engine is mechanically sound (it runs sometimes so must be) then you have narrowed down where to look diagnostically. You will need a wiring diagram and a good voltmeter to do meaningful test. It could be a bad main relay, failed sensors in the distributor (I have seen this cause your type of problem on Toyotas), a bad ignition switch or many other things. Get a wiring diagram, study it and know where to look for voltage when the car fails to start and run.