I've got an 02 4.0 4x4 and I like it. I've towed a little bit with it and it does ok but not great, towed some fairly heave loads but not, never towed a car though. Considering mine's got 4:10 gears in rear it's a little gutless.
I believe Ford brochure has the 4.6 able to tow a car sized load a buddy of mine just bought one in a 4.0 and loves it. He pulls a triple quad trailer with it and says it pulls ok thanks to the 4.10 gearing but wishes he would of popped for the v8.