There are lots of guys on this board with over 300k. Search and you'll find them.

 

Get the Fie Fo
Mo powuh

 

Fuelly.com Look em up and you can see what mileage folks are getting...

 

I had the 4.6 in my 97 SCrew. It was reliable and on the highway I could get about 20 mpg. I now have the 5.4 in my 07 FX4 and I can honestly say that on the highway I get very close to the same. The 5.4 has more power and is much more responsive. I tow a 5000 lb. trailer behind me and hardly know its there. The fuel economy difference is hardly negligable.

I personally like the 5.4

 

My 02 is an FX4 Screw and it has the 4.6l. Average 13-15 on my daily commute, powers not bad, can't wait for the kids to get out of school so I can add more


Delete My comment GLC missed the part where he said what year models he was looking at

 

I have a buddy with a 97 4.6 he has 360K miles.. Only thing he ever did was replace the tranny and water pump.

I have a 2000 5.4 with 211k and I have had to rebuild the tranny
repair two spark plug blowouts
replace intake manifold.
have several broken exhaust studs.
two vacuum line leaks
and a lean code that I could never fix that finally just decided to go off

That stuff would have cost me more than I paid for the truck if i had to have it done. Seeing how i did it myself i was able to get by.

Personally, reading about all the problems the 5.4l had/have I would rather have a 4.6 for reliability.