Air Intake Vaccum/Voltmeter Guage Wiring Confusion from Previous Owner

Hey Tacoma World, Looking for input.

I bought an 08 Gen 2 Tacoma access cab, and the driver's side dash Pillar was installed with an air intake and voltmeter gauges. Odd, since it's a 2.7 L engine, and I have no idea why these were previously installed. Anyways, Switched out my speakers this morning, and took it for a test run after to beef up the alternator. Gauges were working, no power.

I then took a look at the fuse box....I cannot understand for the life of me how these were actually wired, as it looks extremely unprofessional. Look like they put terminals at the end of wires and jammed them into the fuse box. Also looks like there's an adapter attached (black box).

Can someone break down this whole wiring scenario for me and let me know what I can do to fix this mess? I appreciate your expertise in advance. I find Tacoma World has been an unbelievable help for me to learn new things an save money and DIY.

Thank you everyone!

 

This is why I always buy stock vehicles. Can't trust people to do stuff the correct way. Remove all wiring that the previous owner added, leave the gauges in their location or go to the junkyard and get a replacement trim piece. This is not a hi performance truck. No need to have those gauges.