In some cases, it may be the fuel pump is acting intermitently . In that case you need to hook-up a fuel-pressure gauge to see if you are getting any fuel pressure during cranking .There is a test port on the fuel rail (my 2003 V-10 has it on the passenger side somewhat near injector #4 area ). Also the fuel-filter , does it need to be changed .
One quick and dirty way of checking the spark is to remove the easiest COP and put an older/spare spark plug on it then ground the plug (not on fuel rail of course ) . Your helper cranks the engine , you check for spark , if there is spark then move on to fuel .
Good luck guys,