Thought it was fuel sending unit, but maybe not?
 

The other day I was driving, and noticed that the gas light came on. however, just the past night, I filled it to about half tank. Then I start to drive, and the needle goes back up. Throughout driving and stopping and idleing, I can literally watch the needle go up and down. Same thing with the trip meter on the OBC. Can literally watch it sporadically fly up and down.

anyone have any ideas? I know the sending units usually give you empty or half full readings