I had a 2003 4-Runner V8 Limited. it was a beautiful truck, powerful and quiet. it had no problem pulling our 3,500lb Mobius and single-axle trailer.
BUT when I changed boat to a CC SV-211 on a tandem axle trailer, we almost killed the poor truck. In particular, the gas shocks blew up twice (which cost about 1,000$ to fix each time). The truck had problems pulling at higher speeds (over 110 km/h) and drank gasoline like a college student drinks beer.
We ended up selling the 4-Runner and lost a lot of money doing so. We bought a Pathfinder, and this time we were careful to choose a base model without gas shocks.
I don't think they're bad trucks, it probaby had something to do with it being the first year of the new model, so maybe some wrinkles had to be ironed out...