Cranks but won't start

Originally would start after long cranking, problem got progressively worse. Now will not start at all. No spark and no injector spray. Have replaced ICM, rotor, cap, fuel pump relay. When it did start it was fine rest of the day but after sitting overnight back to no start. Hard start was accompanied by backfire when finally firing. I also disconnected fuel line at filter and turned ignition on to test fuel pump. It seems to be pumping fine.