Flickering head lights, what am I missing

Grounds ?

Output stud of the alternator?
the out put stud of the alternator has a 4 G wire that goes directly to the starter relay stud.
The starter relay stud has a 4G wire that goes to the starter stud,
The starter stud has a 2G cable that goes to the rear battery disconnect, then another 2G to the battery.

Grounds
battery negative post to the starter mounting post is a 2G cable
starter mount post to a stud on the fender is a 12 G wire, and at the stud is where I ground the voltage regulator, and other misc grounds
I have the headlights, ECU, Fuel Pump, electric fan all on relays