98 F-150 won't start
 

I've been chasing this gremlin for 3 years and it's finally stopped me. Truck won't start, no gauge cycle when the key goes to run, starter doesn't spin, click, nothing. Can get the starter to spin with a screwdriver across the relay, but engine won't fire. Usually, the problem "fixes" itself in 10-15 min, never been this long. No power to "hot in run/start" fuses under dash, but the power distro. center is all hot. The ignition switch is new and I even retried the old one. Ideas?