I agree with bogdog about the 3.slo. I drove a 4Runner that had the 3.0 and it felt no stronger than teh 22RE one I was driving just prior to.
I remember seeing the articles he is talking about too. I have the 3.4 in my Taco and it has been a fantastic motor.
I found this:
ORS is usually pretty $$ though. I am sure there is something on pirate 4x4.
You could always do the Mercedes diesel swap that seems to be getting popular.