Good cranking power, will not start

From your description it sounds like the problem was there earlier this afternoon then disappeared then has come back, now I suppose with extended cranking there will be a Check Engine Light on when it does start. If you have a fuel pressure tester you might consider starting there. Good luck

You need to verify fuel pressure/volume. If you have provided a substitute source of fuel (starting fluid), and it tried to start--you must confirm sufficient pressure and volume of fuel.