87 GT that had sat for a long while. New fuel pump, pressure 42 PSI @ schrader valve with engine off. New ignition components, plugs and wires, dist cap and rotor, ignition module checks okay-and the two spares that came with car, both ignition coils are good, also had a "spare" distributor in car, Did replace some wire on the primary side. High voltage to the plugs checks out okay. Engine ran for a few seconds with starting fluid. Compression on #1,3,5 100, 105, 105 PSI
two things make the car run spark, and fuel. the fact that you replaced the electric side and it started for the most part rules out spark. you said it ran as long as it had starting fluid, that means it ran as long as it had fuel. it could be plugged or bad fuel injectors , personally I like to try the simplest first . So to me it sounds like it could be a plugged fuel filter, I would look at it first . do you know when it was change last , if it's been awhile I would try changing it and see what happens. Hope this helps.
Looking at the electrical issues, check both injector fuses. Pull them completely out and look at them. Check the vacuum on the fuel pressure regulator. You can pull the small plastic line from the MAP sensor and apply about 5-10 inches of vacuum with a MightyVac hand pump and see if it holds. If not, you could have a broken line. Probably not the pressure regulator since it will hold pressure. Your vacuum pump would also probably pull some fuel out if the diaphragm were bad.
Since the car sat for a while and considering your troubleshooting my first suspect would be clogged injectors.
However before going there lets check a few things. If the ECM isn't running it won't fire the injectors. The ignition system will operate without the ECM so the fact that it fired on starting fluid doesn't eliminate the ECM not running. If your ECM isn't running the most likely suspect of that is that the ECM isn't getting power.
So first thing is to note does the check engine light come on with the key on engine off? It should. Does the fuel pump run for two seconds when you first turn the key on (no cranking) and then does it shut off? It should. If the answer to both of these questions is no, then you need to look at why the ECM isn't running. If one or both is yes then the ECM is running.
If you have both of the previous questions as yes, then the next thing to do is to just bump the starter and see if the fuel pump turns on for two seconds and then turns off again. If so that indicates that the ignition system is sending a signal to the ECM. Note - this test is only valid with ONLY a bump of the starter. If you crank the engine with the starter you will build up oil pressure. The fuel pump relay has a back up redundancy in the oil pressure switch. If oil pressure is built up the oil pressure switch will turn on and the fuel pump will run.
So now if questions 1, 2 and 3 are all that they are working properly, then the thing to do is to pull the injectors and soak their tips in injector cleaning fluid overnight. That will free the injectors. Replace the O rings on the injectors before re installing them.