Starting issues, fuel pump?

I have a 1990 F-250, it had ran a bit rough for a day, then just died and wont start now. I tried starting it after it died, while it was still warm, but no luck. I tried using starting fluid (only while cranking, and in short bursts), and it wont start. I have replaced the batteries, the GP's, the GP relay, and fuel filter. Still no change.

I disconnected the threaded fuel intake going from the fuel pump to the filter cap, and when cranking, it just comes out in little blurps, no steady stream and doesnt seem like much pressure. Didnt run it dry, still have half a tank of fuel, however last year my employee who used to use my truck (emphasis on USED to) ran it dry several times.

Any suggestions? Maybe the fuel pump, or something else? And if it is the fuel pump, is it better to replace it, or remove it cap it and do a generic electric pump?

Thanks!