just purchesed 91 mr2

i just bought a 91 mr2 n/a the motor is tired and in need of a rebuild. it seems to me that it had lost alot of its power and torque. if any one knows of any good componets for all the internals or if i should just go for the 3sgte swap let me know ... cause my car is a dog and i need to bring it back to life quick ...... and if anyone has info on the 3sgte swap or if the stock pistons and crank are forged (cos toyota dosnt have a clue ) let me know ... i appreicate it