Yusuf, yes many members still have these Pajero Mini, and post here.
Post more details about your Pajero Mini, like model, transmission type auto or manual, engine turbo or non-turbo, and how do you know its heating up? Does engine shuts off automatically when stuck in traffic and heat needle is above half marker?
I own one, and have tuned it to be on factory configuration, and so far I've not experienced any heating issues, have the radiator fan on clutch and thermostat valve intact.
Also, removing thermostat valve will make your vehicle run rich, and plugs will start to have more carbon on them, and fuel average will be bad. Engine's optimal temperature is around 88c.
Also, if its a auto transmission, do you set it to N when stopped in stuck traffic? many people don't do this, and engine keeps pushing on while they press break pedal. This makes engine heat up really quickly.