Headlights trying to have their own dance party...

This has me stumped. After driving for a little while, around 10-20 mins, my headlights start flickering on and off almost like a strobe light. I've had this problem for a little while and have read post after post trying to figure out how to fix it.
So far I've:
Cleaned all the wire connections I can find
Bought all new bulbs and cleaned the contact points
Installed a new turn signal switch
Replaced all the fuses

Ack! Help! The only other thing I can think it might be is the headlight switch?