Here are the testing instructions for test the Fuel Rail Pressure and Temperature Sensor that the dealer says is not involved in controlling fuel pressure. Ask your mechanic to test this sensor: http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?fromSearchPage=true&pageId=0900c152801e8f59&partName=Fuel+Rail+Pressure%26Temperature++FRPT++Sensor&partId=0900c152801e8f59