Isuzu Rodeo, 1994, 3.2v6, 2WD, autotransm

Hi, this is my wife suv, it has a lose of power, especially when she stop at the red light, I already change: spark plugs, air filter, and have putted on it about 4 fuel injectors cleaner with each tanks, this is a really desperate situation, she told me that the car turned off by its own once a time she was driving it on reverse, I did not change the wires because she told me that she did it less than 10k miles ago, please help me, I don't want to spent money trying to figure out by my own. Thanks, I like this page, reply me asap.