I have a 1996 V8 ford explorer AWD. Sometimes it will start, but when I turn it off it will trunover but will not start again.

I have replaced the plugs and wires and coil, also replaced the fuel filter. I can hear the fuel pump turn on when I turn the key.

It started this morning and I drove it down the street. I turned the motor off and not it will turnover but will not crank. Any ideas?

Thanks