ya might see if the engine thats in it might just need a tuneup or some minor engine work,it would be less expensive. unless ya have a lot of cash to spend a new engine wont change the way it drives,thats what suspension and tire pressure do. if the engine is definately shot then yea but id look at it real good.
This vehicle gets excellent reviews and with a 4.0L engine, it ought to be pretty peppy. Something must be really wrong here. Get it tuned up, ask a mechanic who is familiar with this vehicle... probably at a Toyota dealer. If the motor is so worn out that it has lost that much power... something else is going on here that we don't know about.
I have seen clogged exhaust systems that completely rob the car of all power. You'd be surprised. Get a GOOD mechanic to see what's going on... a piece of the puzzle is missing here. Have it checked out before you blow a ton of money on a new motor... that you probably don't need anyway.