After extensive research on owners experiencing fuel delivery problems I can not find an answer to my particular problem. Here goes. My car is a 2003 Duratec with only 72000 miles. I've only had it for the past 1500 miles and twice in those miles I've had it want to run very rough and then stall after starting either a warm or cold engine. After cycling the switch on and off and at least a dozen or so rough running cycles it will start and run as if nothing has happened! I spent close to ten minutes the first time this happened getting it started. Today at Autozone I got a P0191 code. It suggests 1:A fuel pump 2: Defective fuel pressure regulator 3:A fuel rail pressure sensor or 4: a fuel filter. I have no driveability problems whatsoever otherwize and this happens about every 500 miles. Fuel filter was changed less then 10k ago. I vote for the fuel pump and regulator are bad but hate to start throwing money at parts I don't need esp since this only happens every 500 miles or so. Any quick hints or has someone else experienced this?