OK, Bought a 07 with a couple problems today.

[donjetman]

Forgot about this pic. Took it sitting in the parking lot at work because of the mileage.
This was before I changed the oil pump. Also shows fuel empty when full and turns the check engine on. After about 20 miles the gauge starts working again.
View attachment 443335

My fuel gauge does something similar. Fill it and it reads empty, after 80 miles are so it reads full. Then when its used 13+ gals it reads various amounts between full and empty?
I changed the fuel pump/gauge module and nothing changed?

 

[SpareParts]

I have no idea. I assumed it was the sender in the tank, but I guess not. Maybe the problem is the stepper motor in the cluster?