2001 Hyundai Accent unknown

hi my car has been acting up lately wat it does is that i will onyl rev up to 3000 rpm and wont go higher andwhile giving it gas there is a loud whistleing sound coming from the motor and there is absolutley no power i have to down shiift to make it up small hills
it did this once but then went away
engine light is not on either
help need my car back
thanks