A year ago my 94 4.0 was having intermittent start problems, under varying conditions. No codes were logging. After replacing the fuel pump with no fix, and trying all the usual troubleshooting of relays, connections, etc. I went back to basics and checked the three electrical grounds I found under the hood. They were all degraded by dirt, old paint, and corrosion. After cleaning them up and applying a dielectric grease for protection, I have not had anymore problems for 12+ months. So when troubleshooting be sure to not overlook the basics, i.e. does it have power AND a ground?
See G101 and G103 for example on the attached wiring diagram.