I have a 2003 f150 4.2 a/t. at idle and lower rpm's it has an irregular, but constant misfire. I replaced the plugs about three months back, and a fuel filter about a year ago, but this just started. I pulled the plugs and they are burning fine. I just put wires and a coil pack on it this week and it is still missing. I cant find a vacuum leak anywhere. it was throwing a lean code on bank 1 sensor 1, but that has stopped. when it warms up I plan on pulling the throttle body and giving it a good cleaning. the truck has 140,000 on it and climbing. its a daily driver. I need some help lol I don't know what else to look for. any help is good help

 

A sad update to anyone that has viewed this... The misfire is continuing at idle. It starts rough and is blowing not a lot, but thick white smoke. Checked the coolant and it was super low. I added some to it and I'm going to watch it over the next few days. I'm praying I don't need head gaskets lol

 

Iac idle air control sensor