RPM's occasionally high
 

2003 F150 4x4, V8 motor, RPM's occasionally go to about 1500 when put in park or neutral. I can feel it when in drive as the truck takes off pretty good when break is released. If I shut the thing off and then restart it the rpm's are normal. No check engine light, no nothing. When this happens it is usually after a short drive. Thanks for any help.

check your IAC

How do you check an IAC?

unplug it and see if your idle changes


it coud also be getting dirty so you could pull it off and clean it, I just spray carb cleaner in mine

Thanks for the help. Next time it does it I will unplug.

Yea man the inside of those things can get dirty. I can guarantee you its your IAC, but you wont get a code until its completely gone. When it goes completely sometimes the truck wont stay running even if you are giving it gas. I would replace it just for peace of mind BUT you can take it off(its just two bolts) and clean out the inside of it usually. Use some carb cleaner.

There is a test to see how far off it is from going out that you can do. Go out to your truck and unbolt it and turn it upside down so that you can see the valve on the inside. Have someone turn your key to the "on" position without starting the truck, and if it is working properly you will see the valve move on the inside. If it does not then it needs to be cleaned or replaced. Sometimes cleaning it "patches" the problem for a little while, but it will eventually go out and will need to be replaced.

*EDIT* One other thing you can try would be tapping it(not very hard though) with a wrench, hammer, or whatever suits you to get that vavle loose inside of there. Its the same concept as banging on your gas tank to get that fuel pump to kick in.