This is the guy you sold the bumper cover to, it looks great on the car.
I have experience with older diesels, but IF the vacuum pump is similar, you may be near end of life on your vacuum pump diaphragm. The oil is from the crankcase and it indicates a pinhole in the diaphragm. The older pumps were rebuildable, but I used a boneyard pump and it's been fine for 50k miles.
HTH, I'd get it checked out before going out of state.