I have a 2006 f250 crew 4x4. I decided to add lucas oil with my regular oil change and a couple thousand miles into this interval my truck started having idle issues (increase and decrease 100-200 rpm) I have never showed any codes up to this point. Most times starting the motor it will start to fire in a timely matter but it is not a good start like it is not hitting all cylinders right away. It doesn't shake or chug at this point. It got to a point where it would hiccup with cruise on going down the road. I've never had anything happen when the truck was cool its always been warm. I then noticed that i was having some turbo lag as times and when it would spool up it seemed to almost have more power than normal. I then changed both fuel filters and the truck fired right up and let it run outside the shop for at least 30 min then drove it into town and shut it off. It didn't want to start after about 10 min of being shut off. I chugged a couple times and then it started spinning over faster. I then just left the key on for a while to let the fuel pump cycle. It finally started and I made it back to my house. I then loosened the cap for secondary filter and turned the key on to make sure I had fuel getting to the filter and it was. I tightened the lid and it fired right up. I drove it the next couple days with no more new issues and then it wouldn't fire. I loosed the filter cap again and it fired up right away. Later that same day it lost power and it would idle but would not accelerate with the foot pedal until it eventually died. I did the fuel filter trick again and it fired up and I drove it home again. I took it to local shop (I'm a couple hours from ford dealer) and they drove it 40 miles with computer hooked up and couldn't get a code or even a hiccup....what can I do next?

 

Might be a couple of different issues at play.

The irratic idle sounds like a classic case of a dirty EGR valve. I suggest you pull it, and report back with what you find. You are looking for carbon buildup, and is the carbon dry or sticky/greasy. If it is dry, you can try cleaning the valve with carburator cleaner.

The starting issue began right after fuel filter change, so you have to wonder about what went wrong with that. Have you done filters before? What brand filter did you use? Did you prime the system well after installation (idling for 30 mins is not priming). Lastly, what oil do you use and when was it last changed?