(Portland, OR)  --  Police are searching for an armed suspect accused of carjacking a man at gunpoint in southeast Portland.  It happened just after midnight Monday in the parking lot of the Shell Jackson gas station on Southeast 122nd Avenue.  Police say the man pointed a gun at the driver's head and ordered him out of the car.  The stolen vehicle is described as a gray 2005 Porsche Cayenne with Oregon license plate 413-HSE.