i used to have a 94 nissan pickup with the same problem bigbill. i tried everything. in my case it was the clutch safety switch. lay on your back on the driver side floorboard, and look up at where the clutch mounts to the firewall. you will see a switch that gets pushed in when you apply the clutch. attached to the switch are two wires (colors vary, mine were both black). connect these two wires together preferably with t-taps and male spade connectors. this will bypass the switch. HOWEVER: this will also allow you to start your truck in gear with out the clutch being pushed in. Be careful as your truck will lunge forward if it's not in neutral or the clutch isnt pushed in. hope that helps.