I have a 2004 F150 4x4 XLT with a 5.4L.It has 80,000 miles on it.
Just a couple of day ago a vibration started when i reach 45-50mph and then it does it again at around 60mph.
Has anyone else have this problem?

 

sounds like it could be RPM based? can you confirm that? If not it could be a wheel bearing.

 

Had the same problem, but my Service Engine Soon light was on. I was having a misfire in Cylinder 2...changed one plug, and it seems to be fine now! I have a similar truck, too. 06 XLT 5.4 with 74,000.

 

Don't know what the rpm is but its at 45-50mph and again at around 60mph.
Put those mph is when it shifts and the vibration sounds like a rumble strip that last a second or two.

 

no the vibration feels like its coming from the rear

 

Had the same problem, dealer said I need new spark plugs, $900 cost. Does that sound right for just plugs? Got a 07 5.4 liter

 

It has 74k miles

 

I have the exact same problem on my 05 f150 5.4... When i Reach 40-50 mph it Shifts into a higher gear and bogs down and sometimes it jerks like my transmission is slipping but when I press the gas to a high RPM it stop bogging down after 50mph . But their is no shaving in my transmission plug.It's not the spark plugs. I change my spark plugs and it does it still. I had my plugs changed for $300. But that bogging down is so aggravating and i Can't find what the problem is.

 

have you used your E break recently? my dads use to get stuck like 1/2 on and it would vibrate like mad till you stopped put it back on and took it off a few times. his trucks an 04

 

I have an 08 with only 32k miles and mine vibrates at those same speeds...