What sends power to the coil 1997 Nissan Maxima?

Besides what you have mentioned. There is a condensor on the left side of the engine. This has 2 wires, black is common ground for coil and red is common power that goes to condenser.
From there the components are as you mentioned, including signals from the Idle Air Control Valve, (I cannot figure that one out unless this is a signal circuit), eventaully tracking through what seems to be a specialized relay at fuse #33 which is 7.5A and then on to the ON position of the ignition switch. The wire can be traced to other sensors, but I think you covered the rest of them.
It is a complicated signal and I have to assume the power gets jumped up at the condensoer, anothjer word for capacitor, to power the coils.
Do you have 12 volts at the black and red wires common to the coils?
Check that and other mentioned sensors and see where you have 12 volts and where you don't to track down failed part or bad ground.