[LX5liter]

It might be flooding, next time it won't start hold the accelerator pedal to the floor while cranking, this tells the computer not to add any fuel for starting. If it fires up, then you probably have injectors leaking down. If not then maybe your not getting any fuel, or it could be ignition related as well. Do you have spark when it won't start? Do you have a pressure guage hooked up to tell you what the pump/regulator/injectors are doing?
Tell us how it goes.