Might be a disconnected fuel pressure regulator. It's the highest thing on
the top of the engine. Has three fuel hoses attached to  it ,and a thinner
vaccum hose.The vaccum hose may be disconnected.The fuel pump makes about
60psi pressure.The regulator bleeds this down to 29psi.Seems that a full 60
psi may make for bad gas mileage.Dont know if this is how disconnected
regulators work,but worth looking at.You can do this yourself.