If you have spark, fuel, AFM tests OK, if there is compression and timing checks out, you can get some noid lights to test the wiring harness for a ground issue between the injectors and computer, I had this happen to me where the injectors grounded out turning them on all the time,flooding it. It started out where it would stall going over a bump or abruptly stopping finally i started it up one day and it died half block later unable to fire up. You can not use just a test light due to the lack of resistance and will fry the CPU. If it is grounded out the noid light will just stay on while cranking, (indicating the injectors are wide open dumping fuel) if it flashes well that's not your problem ( this proves injectors are getting power the way they are supposed to). My wiring harness chaffed through by the power steering pump where it goes over a hard line. Found it by just wiggling the harness and listening for clicking of it grounding out . I was able to remedy it just by cutting out that chunk of wire and soddered it back together and wrapping the harness in some old rubber hose to prevent this in the future.
