This sounds like the same trouble I had on a
94 GMC 4.3 vortec engine.
It would not start unless I sprayed starter fluid into the intake
When this first started the car would run ok, But then it got so that it would start but only run
at idle speed.
I was convinced that the fuel pump was good because it would squirt gas out when I disconnected the line and turn key on for about a foot.
It turned out to be the fuel pump afterall.
Make sure the fuel pump has enough presure for your car.