Sounds like when you changed the fuel pump, air was introduced into the system. Take the filter or filters off and make sure they are full. Then loosen the injector lines at the injectors and bleed the system by either by useing the manual primer pump if it has one or cranking the engine till you see fuel comming from the lines. With that done, don't assume that the solinoid is working properly. Being a magnetic coil, the windings can be breaking down when it gets warm, then work when it cools off. If it is an external solinoid, try securing it in the run position. (keeping in mind that if this is the problem it will not die when you shut it off, so it would be helpful to have someone available to release it) The other method you could try is to activate the solinoid and leave it set for a while to see if it warms up and releases itself. I would lean toward the solinoid being bad based on your discreption of how it acted. But I have been fooled before. LOL
Just.