The second gen trucks did have a 3.0 v6 option available, but they are fuel injected vs the g54b which is carbed. If you want to go that route, a motor and trans/transfer case from a montero with the wiring and computer could be swapped in. An easier way is to swap in either a starquest (starion/conquest) turbo g54b motor, or swap in a 4g63 from an eclispe. None of these options are easy or cheap - look through the threads and you can look at all these choices done by others to see if its worth it to you. These trucks are quite capable even in stock form if they are working properly - try going over the truck with a tuneup, do a compression check, check timing, cooling system, even the exhaust for restrictions. It will never run like a v8 in stock form, but it will have decent power for its size.