I think I've finally found the cause of my recently-atrocious gas mileage. When the truck is running and for a short time after I shut it off, I can see fuel dripping about twice per second off of what appears to be the fuel pressure regulator. I haven't taken things off to see if that is indeed what's leaking, but if it is the FPR, how hard is it to replace? Or is it just an O-ring seal inside that might be leaking?
Knew there had to be a reason why my truck smells of gasoline after it sits for a few minutes.