Your fuel pump is probably dead or the rubber hose that connects the pump to the tube inside the tank has a split in it. You will need to check the fuel pressure from under the truck seeing as there is no test port on TBI motors or install an adapter in the supply line at the back of the motor where it connects to the TBI.
Your specs should be 9-13 PSI. You can also check the fuel pressure regulator by pinching off the return line to see if the pressure spikes above 13-15 psi. Judging by your symptoms, I would say bad pump.