I have a 1994 corolla and I'm doing a 20v silvertop swap on it. I put the engine on and all the component to have it running. Now when I try to turn the car on it will turn on but it won't stay on.

Make sure the AFM is hooked up and working properly.
You could try jumping the fuel pump interlock to eliminate that possibility.

How long does it run for?
Does it make any difference if you give it any gas?

It will turn on but when I hit gas it shots off. Now when I unplugged the afm stays on and if I hit gas it turns off.