My truck (2002 f150 5.4)has sat for the past 2 days and we have been getting alot of rain lately. I went to start it today and it started ideling really rough and hessitates bad when I hit the gas. Then after a while the check engine light came on. I was reading previous posts and kinda figured it could be a coil pack or the IOC? (dont remember) on the back of the throttle body. Does that sound about right?

Another question is...... are these expensive parts? I am thinking of just taking it to the dealership so I dont have to deal with it and get it fixed quick. Do they charge alot for either of these? Or maybe anything else it could be?

 

Ah the IAC valve, just finished cleaning mine 5 minutes ago, first time I did it, and it solved my erratic idling problem and stalling problem too worth a shot.

 

Head up to Auto Zone , they'll scan that code for free , tell us what code they scanned (the numbers that came up) and you'll get allot help here..

 

Could be a leaking hood seal at the firewall. Since these engines sit so far back a leaky hood seal means water can get to the COP's. You could always remove them and blow some compress air in the holes and around the COP's to dry them out.