I have a 2000 F150 4.6 V8 standard tranny. My problem is when i come to a stop my idle goes low down to 400 up to a grand and then to normal. this only happens when i come to a stop. Do you have any suggestions to what this might be?

 

njb543:

Just my idea...here goes. Had a similar problem on my 89 merc 5.0
The IAC was dirty. Loaded up with carbon deposits. After i spray cleaned it, the idle problem was totally cured. My cost was $4 for the can of throttle body cleaner.

-hooD

 

Probably the IAC valve, but could be the Throttle Position Sensor, the Mass Air Sensor or the Vehicle Speed Sensor.

I would clean the IAC and if that doesn't do it scan for codes.

If you have messsed with the idle speed set screw you may have to go through the idle setting procedure.