I have a 2004 Freestar with a 4.2 engine. Lately the engine is idling at around 1500 rpm. There is no misfire. The only code is the one for high idle. I have swapped the IAC about three times. I have replaced TPS and MAF sensor. I have cleaned the throttle body. Lower and upper intake gaskets are less than two years old. Any ideas? I am about to tear this thing down and start with new gaskets. Can't think of anything else. Anyone have ideas? Fuses? Computer? Fuel pressure? I have looked for vacuum leaks, and can find none. It would take a significant leak to run this fast. 40 mph without touching the gas! I am thinking of buying a ECU. Van is in great condition with 250,000 miles.