I have a1992 Ford f-250 4x4 long bed regular cab with a 5.8L and a E4OD automatic transmission here in the last week I get only 9 mpg highway and it dies while reversing I did a oil change new cap rotor and wires and it still does it any ideas on what I should try next

 

On the driver's side of the fuel rail is a fuel pressure regulator with a vacuum hose connected to the top of it. Pull that hose off and see if any fuel comes out. If it does, the regulator assy must be replaced. It should be held in place by 3 allen head screws.
If the diaphram inside is ruptured fuel gets sucked into the intake causing an excessive fuel condition and poor mileage. Worth checking.

 

Thanks I know I smell gas in the exhaust so I will look at it in the morning and if so I'll get it replaced