I have an 05 Lariat with 145k miles on it. About a month ago I had a misfire code on one cylinder. Since then it's gone from once every couple of days, various cylinders. To now every day. I've had to continue driving it but the last few days it's gotten bad and I hope I didn't do any more damage(cats) but I didn't have a whole lot of choice. I've read every thread I can find and haven't found an exact match. It seems to be worse first thing in the morning, it will be down on power for a few seconds then clear up. It may not return for another 10 or 15 minutes and then cough a little and clear up. Sometimes it will start at the beginning of a hill and not clear up until I'm back on flat, sometimes it will lose power at the top. There is zero predictability to it. I have had codes on almost every cylinder, but no single one has dominated the problem. Twice when it has been real bad I have also gotten a lean code 0174. It had new Motorcraft plugs 25000 miles ago and has run fine until recently. The ticking isn't too bad but I think I'm going to try thicker oil for the summer. It's been a while since I did the fuel filter and since it probably isn't a bad idea I'm going to do that today before I get into more more labor intensive hail marys. Any ideas, thanks.

 

Sounds like a COP problem. If you haven't replaced any I would do the whole set and pay for the FORD COP. I bought some aftermarket ones and chased a two bad ones for a while. Also, I had new plugs put in and ran like crap. Shop cracked two on install. Good luck.

 

While you're under there changing the fuel filter check your fuel pump driver module. They are known to corrode causing random issues. It's mounted on the cross member behind the spare tire. You'll have remove it to see if its corroded. Do a search to see what others have found.