One of my friend said that it can't ...
he's wrong
ok what you do is you
check your ecm for codes and that it's running right in closed loop (flashly on/off as per FSM)
you check your spark plugs/ leads etc
you check/clean all the electrical connectors for sensors, ecu etc
you check all your sensors/leads that you can (with multimeter) using FSM instructions
then if you haven't fixed it ask for help again, if you have reply - how
most everything you need to know you can find on this website but you do need to look read and try to understand what everything does.