About half the time I try to start my truck it'll rev high, then drop to about 300-400rpm and either stall or decide to start, once it's running it's all fine no problems any other time but starting. It was suggested that I try to clean my idle air control valve, but I don't know much about it, I know where it is, but one of the bolts looks almost impossible to get to. So before I go taking this thing off, I want to get some other opinions... Thanks

 

It's a good place to start. Sounds like a possibility.

Cleaning doesnt always work though.

Stand on the passenger side, by the fender...might need a stool if you're short and use your left hand on a ratchet or ratchet wrench. The clip will require you getting your hand back so kneel on the fan shroud.

 

As it was said cleaning it doesn't alway make it work. I cleaned mine when I was having issues and 2-3 days later it was giving me the same issues. So if your going to be taking it off, I'd just replace it.

Wayne

 

It is a really cheap part to replace.

 

I had the same issue on my 5.4 so I went ahead and bought a new one for $35 from advance auto. It was a pain in the butt to replace because I have big hands so I went ahead and removed the throttle body and cleaned it.

 

The check engine light hasn't ever come on though, wouldn't it if the iac was my problem?

 

No.

 

We all know the high idle on start ups is correct and fine. When it comes off down to 300-400 is questionable. With engine warmed up, unplug the IAC and see what the idle is. 450-500 is the target speed, use the screw on throttle body to obtain that. Plug in the IAC and the engine should go back to the normal idle 850-900.

Many years ago we would clean the throttle body with combustion chamber cleaner and a dish washing bottle brush. Sprayed in the cleaner and swabbed out the bore. If you notice, when you remove the intake hose you will see a decal from Ford not to clean the IAC. People got carried away and used incorrect cleaning agents and messed up the IAC and thus premature warranty replacement.

With the history of the truck unknown, its probably best to replace the IAC and then adjust correctly.

 

What adjustment screw are you talking about exactly? when I unplug mine and crank it then let off the gas it dies right out.

 

Oh, my gawd! unplugging wires while the engine is running? on your own truck? The HORROR! Funny, a couple people on this forum jumped all over me when I said did that to mine while trying to diagnose a miss/rough idle...waiting to see if they do the same to you...LOL