Have 04 Freestar SEL 4.2. Getting P0193 (fuel rail pressure sensor circuit high input). Sometimes can drive several days and no code. Then engine light comes on and same P0193 code. Have replaced fuel filter. Can you tell me if this is just the sensor that needs replacing or the fuel pressure regulator? Where is the sensor located and how do you check the pressure. Also, have noticed a vacuum leak sound. How do you check to find the vacuum leak -- could this be the problem with the sensor reading? Thanks.