My truck is a 2000 f150 4.6l and has 38,000 miles on it. My truck is idleing rough do u think its the air idle control valve or something else.

 

Well it very well could be the IAC. Does it drive fine when you are on the throttle? If so, the IAC is the most likely culprit.

Since you have a 4.6, its so easy to clean that thing its not even funny. Like a 10 minute job, if you dont know what you're doing.

 

yeah, it drive fine, but when i'm at a stop light or sitting in traffic, it idles rough. so u thinks its the iac?

 

iac sounds like the problem

 

Never hurts to clean it with t-body cleaner or replace if problem persists. I wouldn't rule out other things, but try the IAC first. I usually noticed mine was acting up on cold wintery days rather than now so...

 

The IAC isn't well known for causing a rough idle, it usually causes erratic idle, no idle, or improper idle speed.

I'd suspect a vacuum leak or improper EGR flow.

Steve

 

Run some Sea Foam through the gas tank and see if it help. Also change the fuel filter if you have not.

 

im having the same problem with my 97 4.6. i cleaned the throttle body, iac valve, and put in a new pcv valve and a new fuel filter. everytime i changed or cleaned one of the listed above it idled smooth for about a minute or two. when i would come back from a little test drive it would idle rough again. any opinions or guesses? i put a new egr valve, iac valve and iac(maybe egr cant remember) sensor about a year and a half ago(dont know if that makes a difference that they are only that old) but i also bought the truck with 66,000 miles on it and now it has 140,000, i never changed the plugs yet and im pretty sure they werent changed before i bought it, could that be makin it idle rough? also i do run lucas inj.cleaner in it now and again. thanks for the help

 

Exactly...I have never seen a IAC cause a rough idle, it regulates the idle speed to compensate for engine load...

Try taking the hose off the EGR and plug it, see if anything changes..tap lightly on the top of it to see if it is sticking.....get some carb cleaner and spray around the intake and vacuum fittings, if there is a leak the motor will stumble....Try cleaning the MAF as well