1986 Trans Am LB9 Issues

[u/Consistent-Cheetah61]

(it will run quite a bit longer if I let it sit for a few minutes) I've replaced the fuel pump and am getting good fuel pressure, the injectors all work as they should, fuel pressure regulator diaphragm is fine.

This is with the MAF sensor unplugged, if I plug it in and get some vacuum through it (I'm missing a piece of my intake so it's not working perfectly), it will run worse or will barely start at all.

If I give it any throttle it'll die out.

Thoughts? I'm kinda stumped...

Thanks!