Which fronterra are you looking at the 2.2 diesel , 2.2 Petrol or the V6 Petrol? Also what are you towing.
I have in the past had 3 Fronteras. 1st was the origonal 2.3 diesel. next was the 2.2 Petrol which was OK but you had to work it hard and it was a bit thirsty when towing, finally was the 2.2 diesel, this was the finest frontera we had, pulled our Lexon without any effort , plenty of torque and good mpg, one of the best tow cars we have had.
If it is a manual check the clutch , whilst not a known problem they have a dual mass fly wheel which can be expensive to replace, also check the service history, ensure oil and filter changes , the fuel filter is akward to change as it is underneath by the chasis. I never had a problem changing ours , but I have heard of others who had a lot of trouble bleeding the system as they got air in the fuel lines, if in doubt get it serviced by a garage.
All in all a very geed vehicle.