You can pull your valve covers and see if the injectors are all squirting oil when the truck is running. If they aren't squirting oil, you can check to see if the screw under the solenoid is tight and also check the clearance. I forget what the clearance should be set at, but I want to say .004 is good and .002 is on the lower limit.
1995 F350 CCLB DRW 4X4 XLT 5 speed 63k miles, 6637, EBPV Delete, non-ebpv turbo pedestal, 3" DP, 4" Diamond Eye Turbo back, US gear overdrive, exhaust brake, gauges
Sold: 1997 F250 Supercab 4x4 XLT (California Model) 178k miles 3" DP, 4" Diamond Eye Turbo back, AFE intake, Swamps AD injectors, Beans Fuel System, EBPV Delete, non-ebpv turbo pedestal, International Bellowed Up Pipes, Stancore GPR.