You state, assuming that I understand what you stated, it's sucking the gas, correct?
Yep, electrical connections and sitting for years.................worse thing you can do is let a truck/car sit for years without attention, condensation in the tank, corrosion, critters eating wires.......time kills more than miles do.
If it's running rich.......O2 or MAP and tube to MAP...........and........well........everything else to consider.