One of my cylinders is running lean. Car has 87000 miles on it. Changed my plugs about 800 miles ago. I noticed my passenger side rear plug was in bad shape when I swapped them. Checked the new plug the other day and it looked bad again. Any suggestions?

 

Is that from running lean, or is it burnt oil? (ash deposits) how are your valve seals?

 

You are correct , that cylinder is burning oil . Since it's burning oil , and if it is actually running lean as well , It's highly likely he needs new intake manifold gaskets .

 

Nothing there to indicate lean.
Do the easiest first: change valve seals.
If it persists, then do as Orange says....intake gaskets.