P1506 Error code help plz !

[sman83]

I have looked throught the forums and various sites to no avail.

This is the last of the error codes that are popping up.

P1506:Idle Air Control Overspeed Error

I replaced the air filter with a Fram-non oiled.
Replaced IAC.
Cleaned MAF.
Checked for vaccum leaks could not find any.

This is on a 99 Mercury Mountaineer 5.0L V8 AWD.

When I first start it warm or cold the idle shoots up to 1200-1500 rpms.
When I shift gears to drive it drops to the near normal 500-600 rpms.
It only really seems to happen when it is in park or sits at a stoplight for awhile. I am also getting terrible gas mileage around 10mpg.

Any help would be much appreciated,as I am driving myself nuts. Its the last error code to deal with !

Thxs in advance

 

[Turdle]

If you have a voltmeter, you might check the Throttle position sensor.

Key on engine off, should be < 1 volt at idle, and rise slowly to aprox 4v WOT
watch for spikes, or for a false reading on return to idle

 

[sman83]

Will do

I am leaving town for the weekend, not taking my vehicle, but when I get back I can grab one from work and give it a try.

Thxs for the info