Idles at low rpm and will not rev up?

This problem is faced by many others too.
First check out this.
If you remove the air intake tube and turn the key on to the run position and get a helper to press the throttle pedal does the throttle plate open?

If it opens, then --
Disconnect the negative battery cable and wait 5 minutes then reconnect. Now with the air intake tube still off get some one to start the car and watch the throttle plate. If it starts it will run rough. If it starts then have them apply throttle and see if it will rev up. If it will not rev up then the electronic throttle body is faulty. If it revs up then reconnect the air tube and disconnect the battery once again to clear the computer of any faults you caused by running it with the air intake tube disconnected.

But if it revs up by this procedure then, throttle body is faulty.