Flickering Lights

Hey,
 
I just got a 1996 Ford Explorer XLT (The gay lightgreen/light blue color) and ive started to notice that whenever i turn the truck on at night, The outside lights flicker on and off. ithought it was the light bulbs and i changed them all. That wasnt it, then i checked the battery, it was full. Does anyone have anyideas on whats wrong with my 96?
 
 
Thanks

Dirty battery cables, half burnt fuse/fusible link or bad wire are the most likely.