... assuming alternator and battery are fine what else could cause low voltage? Nothing on, just an idling/driving car.

 

Loose connections...... Corrosion in wires/battery terminals.... Old/worn wires...... Etc....

 

Ground cable connections next to the coil.

 

So far everything mentioned looks fine and is nice and tight.

 

Where are you measuring the voltage at?

 

I haven't yet, for now I am just going off the stock gauge. Upon start up it reads ~13amp, once the car warms up it drops to the 12-11amp range.

 

That volts, not amp on the gauge. Read it at the battery when you see it low on the gauge. I bet it will read fine at the battery. My theory is that the ignition switch and it's connections cause a voltage drop.

 

Lol... I don't know why I said amps in that post, I wrote voltage in the title, haha.