Congratulations on the purchase of a great vehicle. This model has proven its capabilities in all terrains and conditions.
First of all, don't get worried, everything in these trusty toyotas is fixable, 3L engine is fairly uncomplicated and there are plenty of expert mechanics available. This engine also came in commercial hiluxes so its parts are cheap and easily available.
Which city are you in? If local mechanics are not trustworthy in your area, you can take it to a Toyota dealership for diagnostics. In Lahore, I know of a great mechanic who is also a fellow pakwheeler.
For advice from knowledgeable people, better post this query to the 4x4 section.
Good luck and post a picture of ur prado.