W what causes crank but no start

@debfinnegan you mentioned that you have "checked Sparks battery ignition coils" but did not tell us if you do have a spark when the engine cranks over. You need air, fuel and spark to fire the engine. You most likely have air and if you do have sparks then the issue would be fuel or it does not spark at the right time.

Let us know what exact year and engine size your Corolla is. From what you are describing I would take a closer look at the crankshaft and the camshaft position sensor.

"Intermittent cranking" and "will crank" are mutually exclusive.

If it cranks normally, the battery is OK. If it is intermittent you could have a number of problems.

If it won't start and you have spark while cranking, and it never makes any sign of starting, then turn your attention to fuel injectors, fuel pump, or empty tank.