Pulling the pan is a very smart idea!
While down check the pump gear and pull a bearing cap or two. Check the bearings for wear. Cheap bearings will leave a grayish muck..... as they come apart. Look carefully in the bottom of the oil pan for metal chips or stuff. Sounds like the goo may just be plugging the pick up. But easy check while apart. Good luck... traitor... lol! Just had to do that.
Also check for a bad or clogged PCV of it has one.
