Mustang dies and gauge cluster goes haywire

When was the last time the fuel filter was changed?

Does is die like someone turn off a switch? This is usually electrical.

Try this. Cycle the key on/pause/off several times without cranking. Do you hear the fuel pump run each time? If not, STOP and find out why.

Check the fuel pressure. If it drops this likely indicates the fuel pump is bad or going bad.

Since this is your first Mustang, a set of Ford service manuals, wiring diagram, and PCM manuals maybe a big help. PM if interested in getting a copy for yourself.