This engine is quiet common in a lot of vehicles specially Fortuner, Toyota Hiace etc.
However as Prado is full time 4wd as compared to others maybe this could be the reason for feeling underpower.
If you are comparing it with some diesel version with same capacity engine than definitely it is underpower.
Last September I was coming from Isl-Lhe on motorway on our return journey from Hunza around 3 am at night.
My friend was driving my 1999 Toyota Surf with 1KZ-TE @ 110 km/h and a Prado probably 2010 model crossed us at very high speed, my friend throttled to check the speed of Prado and after 5 mins we crossed it on 160 km/h @3000 rpm only. The only reason I asked my friend not to go beyond that speed was my old tyres otherwise it could have gone upto 180km/h i.e the max limit of my speedometer.
And the Prado guy was pushing his best to catch us but he hardly managed 145 km/h max.
That being said it seems its little underpower considering its full time 4wd.