Four Plaid Pantry stores in Portland were robbed this week and the break in the case came Tuesday morning.  The Plaid Pantry at Northeast 15th and Broadway was robbed and police were able to chase the suspect in a stolen car.  They used spike strips to stop the car but the driver got out and ran.  A K-9 officer tracked him down.  Police say 24-year-old Demarcus Vance is responsible for all of the robberies.  In each instance he would claim to have a gun while demanding money but no one was hurt.  The other stores that were robbed are at 5146 SE Holgate Blvd., 7144 N.E. Killingsworth St., and 6510 N. Greeley Ave.