I bought a 1997 F150 4x4 with a 4.6 in ita couple of weeks ago. It has a couple of problems with it first the truck run fine when i bought it then a week ago it started running really rich almost to the point that it almost wants to choke off at a stop. Once i get to going again it runs fine. Another problem that it has is that when it is stopped the cold air intake makes a loud horn like sound. when the hood is open you can hear the intake sucking in air as soon as you hit the gas again it will completly stop making the sound. Was wondering if they were caused by the same problem. Or were they from two differant problems.

 

Does the CAI filter need cleaning? A dirty filter would cause a rich condition, more fuel than air. A injector hanging open too long could also be a problem.
Do you have a CEL [check engine light]?

 

Clean the MAF with MAF cleaner and see if it improves first.

 

Torkum No I do not have a CEL popping on. When I took it to Advance to tun the codes on it they said that it could be the idle arm. After looking back through a couple of the problems with other trucks on this site I am starting to beleive the exact same thing.

 

Sure they didn't say idle air controller [IAC]? The idle arm is a steering component