2007 Lincoln Navigator engine issues
I recently purchased a 07 Lincoln Navigator L, has the 5.4 with 144xxx miles. At around 40-55 mph it starts getting this "quick dip in rpms" almost like a miss. When idling, taking off or on the interstate I don't get this issue. Only when driving city. I changed all ignition coils and spark plugs. I also ran seafoam through the tank twice. Still having the same issue! Please help
How old are your air and fuel filters? Is fuel pressure OK? Did you scan for codes and live data?