I know my dad's '94 V10 isn't running on all 10...I don't know why, but it really sucks to drive because of no power.

 

Have you checked the injectors? Could be either an injector is not firing due to an electrical problem or an injector being plugged on the inlet side. You can either check each injector with a noid light, or start on one bank of the engine (with it idling) and unplug an injector. If the idle changes (lopes) then you know that the unplugged injector works. Reconnect it and go to the next injector. If the idle does not change, then there is your faulty injector.

 

I'll suggest that to him...I'm also thinking that he hasn't done plugs, wire, cap, rotor and the works and that is what is causing one or more cylinder to be down...Or being as he bought it use and torn up (for a ranch truck), that the motor has been trashed and has f---ed up compression in one or more cylinder.

 

If that is the case, then it sounds like time to perform a complete rebuild. Replacing parts here and there is like applying a band-aid to a major wound. When I rebuilt my 5.2, I re-used the cam, crank, pistons, and rods. Everything was checked for tolerance and the cylinders were honed. Rebuilds do not have to cost an arm and a leg.