Your Frontera is in Limp mode and it will stay that way until the ECU fault codes are cleared.
First of all though it would be wise to get a note of the fault codes to find out whatever put it in limp mode in the first place.
A couple of important points about this model,
It will go into limp mode without displaying any illumination of the Engine management light which is unlike most vehicles,
Some of the situations that will send it into limp mode are almost nothing important at all,
But in all cases you will have to get too a garage who have tech 2 reading capabilities or you can pick up a tech 2 connector for a laptop off ebay and download free clone software like I did here
http://www.maxsonic.co.uk/download/opeltech2.zip
and do it yourself.
Nigel, April 2007