car shuts down

https://www.2carpros.com/articles/car-cranks-but-wont-start

Next time it refuses to start don't wait for it to make up its mind-do below immediately to determine if its fuel or spark problem

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine atleast 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 okay-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,cap and rotor,distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it and keep testing

I do hear the fuel pump come on . What is the sending unit? My fuel is working ca it still be faulty?

Do you hear the fuel pump come On when you turn key on? If not check fuel pump fuse and fuel pump relay if okay-check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator

I do hear the fuel pump come on and yes there is pressure it has been checked. I changed the fuel filter, spark plugs, module, coil packs, wires this morning. The car is running so good now power not sluggish. When I stopped to run in the store today I got back in car and it turned over but wouldnt start. Waited 20 min. and it stated right up. The other day when I was changing the plugs one of then was filled and emerged in oil from the gasket leaking I do know that this plug remains submerged in oil. Now what could it be?