Unfortunately the search engine doesn't allow me to search for IAC and most people don't post as Idle air controller so here goes. My 01 screw 5.4 started running rough and the exhaust smelled of sulfur and a little gas. It threw a code for #3 cylinder misfire so I changed the plug which did nothing then I changed the coil and that took care of the code and the smell. It runs a little better but idle and low speed is definitely lacking and hesitating, it comes out of it at high RPM's but still doesn't feel right. I'm trying to find some links for IAC pictures or maybe I'm going down the wrong road completely and someone has a better idea for me any help would be great.

 

Check your EGR for carbon buildup and the EGR ports in the throttle body.

 

would that cause an instant performance change? I didn't think build up because the problem happened instantly. I will check it though

 

Yeah , like torkum suggests cleaning your TB is a good idea and it's a good chance that's the problem BUT, you could still have a misfireing cylinder or bad COP - Good news is that they don't generaly effect the idle unless primary and secondary has failed, not likely..So it's Throttle body /ports, IAC and/or MAF sensors..

The IAC on the 5.4L -



The part to clean -

 

Where the Maf wire is inside the intake , clean this as well w/ brake cleaner or MAF cleaner .. After all that Reboot the PCM , you should have your performance back and then some.

 

If you want the truck to run like new and you have allot of miles on it - head over to Global Automotive , an eBay store and purchase 8 new COPs an F150 kit for $96 - a set of new COPs wakes your motor back up to what it should be , especially a 5.4L..