Two subs combined for Preston as they snatched victory in the first minute of injury time at the end of the match. Agyemang crossed the ball for Lewis Neal to slot home the winner.
Preston have now won three out of the last four including the last two away from home after waiting for six months for any kind of away victory. The Whites now head home where they will face Scunthorpe and Cardiff before the New Year when they will look to push further up the table.