My truck had high idling then it would die out,now it cranks but won't start

pathfinder1962

I have a 1994 Ford Ranger.It started out with high idling then the idling would slow down the truck acted like it wanted to die out.My truck has even stopped on the road while driving it,it completed had gone dead.Last time I got in my truck which was recent I cranked my truck up the idle was too fast and it died out completely.I tried to restart it and all it does now is crank but won't start.
I've changed out many parts already..I put in a new battery,new fuel pump,distributor,solenoid,inertia switch
I get spark,fire,fuel just can't seem to figure out what else to check.
I'm a Veteran and I can't get to my VA appointments because my truck isn't reliable right now.

Mr_Shiftright

Have you tested the crankshaft positioning sensor?

http://easyautodiagnostics.com/misc-index/ckp-cmp-sensor-basics-1