It could be a number of things. 1 is check your air filter. That shouldn't cause your truck to dye so much, but it could help a lot in this situation. 2 give your pathfinder a tune up. It doesnt cost a whole lot, and it is pretty easy to do. Just get some sparck plugs, wires, distrubutor cap and rotor. 3 maybe it could be your pvc valve. I dont know if the 92 pathfinders have this or not, but I know my 95 pathfinder does. I dont think its your fuel pump that much, because like you said, it either runs or it dosent. Changing the fuel filter was a good idea, because my pathfinder had some of the same symptoms yours has and getting a new fuel filter fixed about 60% of the problem.