I thought I answered the porch question in my first post:
For the last year, if I would leave somewhere with the other dogs, he would go downstairs to my neighbor (duplex). He started to poop on the porch when I would leave him with my neighbor, who was home.
Seems, he's only pooping on the porch when you've left him... You *leave* him at home b/c you've gone out with the other dog and he poops on the neighbor's porch. You *leave* him with the neighbor, and he poops on the porch.
Two things are consistent: YOU LEAVING him (which may be causing a bit of stress, which manifests itself as a house-training problem and the PORCH, which was probably a coincidence the first time, but then it became a habit to go there when stressed.
(And yes, the link was in response to Annie asking if all my articles were in one place.)