Car sometimes will not start

I have seen this problem before the ignition switch goes bad and needs to be replaced here are diagrams to show you how to do the job (below).

Check out the diagrams (below). Please let us know if you need anything else to get the problem fixed.

Cheers

You need to confirm the actual fuel pressure by using a fuel pressure gauge. When the pressure is up to standards then go to the ignition system and check for spark.

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can only be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off. Just seeing fuel in the line is not acceptable.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.

Inspect and test the CPS.

Crankshaft Position Sensor (7x) (3.1L VIN M)On lower right of engine, under exhaust manifold. See Fig. 2.
Crankshaft Position Sensor (24x) (3.1L VIN M)Right front of engine. See

Try resetting the theft device on the car. also see if there are any iginiton pulses, no pulses , no injectors will work... here is for resetting theft..

Cranks but no start condition:

Get a helper disconnect a spark plug wire or 2 and ground it to the engine at least 3/16 away from ground -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, Do you hear the fuel pump come On when you turn key on? If not check fuel pump fuse and fuel pump relay if so, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, coil's resistances, distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it.

So does the engine sound different when cranking? like it isn't smooth. Is the check engine light on? if so need to scan for codes, this may help find out what is wrong.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

A scan of the PCM will most likely tell which sensor is bad, cam or crank sensor.

Need to verify injector pulse. Use a noid light or a test light. One side of every injector plug has power. The PCM uses ground to trigger it, so find the power side and then switch the test light clamp onto the +battery post, have someone crank the engine and the opposite side of the injector plug should light the light in flashes. If not it is missing injector pulse.