1991 Nissan Truck fuel pump whines when in drive

I have a 1991 Nissan Truck with the ka24e engine. When the truck starts to move the fuel pump begins to whine. When the pump does whine the truck will bearly rev up past 2000 rpms, and when it does it spits, sputters and coughs. There is an intermitten miss at the idle speed no matter the engine temp. I have replaced the fuel pump, injectors, pressure regulator. I have also checked the ignition module and coil. The truck is no longer throwing any diagnostic codes. The codes it did throw were for the ignition coil (fixed), temp sending unit (cleaned), the Air flow meter (fixed). The truck acts like it is loosing vaccuum, but all of the vaccuum lines are intact and do not leak. Please help. I am about ready to shoot the truck!