I have a '98 4X4 ORP 5.4L, with the towing package. It has more than adequate power. I could have gotten by with the 4.6L probably, but i wanted the extra power I don't have any engine problems with mine, just door crack on the drivers side. I think i average about 12.5mpg.

I've heard people say that the 4.6 gets better gas mileage, and i've heard people say that there isn't that much of a difference in gas mileage between both engines. I don't think you can go wrong either way.