Drew Stanton suffered a Grade 3 shoulder separation of his left (non-throwing) arm in Detroit's 23-20 overtime win over Tampa Bay, reports The Detroit News.   The play occurred late in the second quarter when Stanton was flushed out of the pocket and brought down while looking for an open receiver downfield.   He was visibly in pain, but returned from halftime to guide the Lions to victory, finishing with 252 yards and a touchdown on 23-of-37 passing.  The Lions now have three injured quartebacks to choose from on their roster.