Won't start. Fuel injectors?

I have a 1998 Chevy S-10. It has a 4.3, its a 4x4, and a manual. Several months ago I began having problems every once in a while with it starting after it sat overnight. If I left it and came back later it would usually start. I soon learned that if I just kept cranking that eventually it would start. Now that doesn't even work.

The pump is on, I checked and have the proper fuel pressure, and I even jumped out the relay to make sure the pump stays on. It won't fire at all.

It will fire with starter fluid, so I must be getting spark, but it justs burns that up and dies.

Also, I don't show any codes. I did show a map sensor code after I had been messing with it, but I think that was because I was trying to start it with the starter fluid and I didn't have the air intake on.

I feel that none of the injectors are firing, but on a CSEFI system I believe this is difficult to check.

What would cause none of my injectors to work? PCM? Any other thoughts?

Thanks.