Ok, So I have been running down every wire on the car to make sure everything is all good.

I came across this wire on the firewall passenger side. It is Black along with a blue and a brown wire.

Any idea where it goes to?

What year bird?

1967. Since nobody else answered, I will try and makes some guesses based on the wiring diagram and memory. Your photo does not show at work.

Brown might actually be black/orange which is the blower motor. Blue is the oil pressure switch on the engine.

I'm thinking your black wire might be the one running down to the tranny to activate the kickdown solenoid? The factory did not show that wire on the wiring diagram. It's shown on the '68 diagram.

I think it is power for the blower motor on non A/C cars. On A/C cars, the blower is powered through a separate A/C wiring harness, and the blower motor wire in the engine harness is not used.

Well, now that I can see the photo, I am thinking you have some non-factory wiring there and all bets are off. There is no brown wire on the factory wiring diagram for the engine compartment and that blue wire looks to light colored to be the dark blue for the oil pressure switch. That orange wire also looks interesting as the only orange wire up from runs to the alternator

I see what appears to be the blower motor wire in the lower right corner below the orange wire.

Are there any other signs that somebody had installed an aftermarket alarm system on the car? Extra holes in an inner fender for an alarm horn?

I had an idea and went to the supplimental '67 Firebird Service Manual.

I can't remember if you have a hood tach or not. It has black, brown and gray wires. The black is the ground.

No hood tach, but it has the wiring harness for the console clock.

I installed one of those too (not a factory install). That clock harness attached to the underdash main harness. So does the center console harness.