fuel pressure 86' 420sel

[E150GT]

To change out the fuel injector seals in an 86'420sel, does the fuel pressure in the lines need to be relieved? If so is it relieved by loosening the nut in the back of the fuel distributor? Also, my fuel distrubutor has what looks like oil at the seams where it mounts to the air flow meter. Would that be oil or gas or a combo? The reason I ask is because after a hard run I can smell gasoline in the motor. If I look at the engine, I see one injector that has crud all built up on it while the others are clean. Thanks for the repllies.