Not really sure where to start, but at times, my RPMs fluctuate. Yesterday while driving home with the cruise set, it felt like it was laggin at times. Also when I'm sittin at a stop sign or something, it goes crazy. Today my old lady was like what the hell is goin on. I just changed the fuel filter, so I know it's not that. I read somewhere it could be the EGR valve, whatever that is. But yesterday was the first time it lagged like that with the cruise control on. I didn't lose any speed, but you could definately feel something is going on. Any ideas? Thanks
No check engine light what so ever. It's an 06 XLT with the 6.0 powerstroke.