Ran out of gas. Haven't done that in twenty years. My gauge read 1/3 full. I have a 96 LT4. After my last fill-up, I selected fuel info "average mileage" and pushed reset fuel. like the owners manual said. My gauge hasn't come down from full after 60 miles, and my "miles to go" read out keeps climbing, now reading 400 till empty. Am I an idiot and don't know how to reset this, or is there a gauge problem?