I have spent MANY hours underneath this bus today trying to figure out what's wrong, but have only been able to correct one thing. The bus wouldnt come out of idle because the spring on the throttle cable was bent, stuck, and had a stick or something jammed in there.. god only knows how that got there.
I still havent figured out what the issue is with the oil pressure, but I'm going to pull out the pump, clean the filter and see what happens then.