toy3vze

I just bought a 1990 pickup with the 3.0 3vze efi motor. When I bought it, it started fine. I drove about 20 miles to the interstate, stopped to get gas. After I filled the tank it would not start back up. I sprayed started fluid in it and it didn't help. Checked the plug wires and a couple were bad. I roll started it and drove it about an hr home.the next day I changed all the plugs and wires. It started fine when it was cold. Drove it for a while and then stopped it and it would not start back up unless I roll started it. After I changed the plugs and plug wires it seems like it wants to start initially but then putters and dies. So if it is hot when I try to start it I have to pump the gas and it will rev up and start, then release the throttle and it will continue to idle. If I don't pump the gas when I try to start it, it will try to start then die, after it has done that I try to start it and pump the gas but that fails also. So I have to wait a couple hours to start it or roll start it. I've also noticed that there is a vacuum hose that is disconnected and plugged. I looked it up and I believe the diagram said it goes to the (fpu). When I unplug it and put it in it's normal place it idles rough and wants to die sometimes it succeeds and dies, but if given throttle runs fine. When disconnected or if a plug is placed in the end of the hose it idles fine. There is no check engine lights on but I checked to see if there were any obd codes and it gave me code 12. I looked that up and found that the fault location = engine speed (rpm) sensor-circuit and it says the probable cause = wiring, rpm sensor, ignition module, ECM. I don't even know where to begin to try to find the problems or how to check / test any of those issues to try to locate the exact problems. I will try to get pictures if everything posted tomorrow. Any help will be greatly appreciated. I am on a budget and will try to do any and all work myself. And I'm not too familiar with all the abbreviations (fpu) and (ECM) ect.
Also I noticed the hose coming from the valve cover that goes into the air intake is missing and the factory air intake hose looks like it might have been changed b/c there is no place for a hose to go into it. I base that if if pictures I've seen of other engines I'll try to post pictures tomorrow. Thanks again for all help!!