Did you do fuel pressure test yourself? What was reading? Thanks
Ok..So if it runs on starting fluid this proves spark, timing, and engine mechanical is good which brings us to injector pulse...When it wont start disconnect each injector one at a time to see if it starts or check resistance of injectors..They should be 1.95-2.3 ohms if out of range replace injectors...I've seen injectors short out causing no injector pulse..if that doesnt help I would moniter power/grounds on PCM during problem if good replace PCM. Let me know if you have questions, thanks.
Ok, then just check the resistance of the one injector...If good verify it is not getting good ground pulse from ECM/PCM when it will not start..if not verify ECM/PCM has good power/grounds and replace. You can get a used one from www.car-parts.com to save money. Let me know if you have questions, thanks.