The Ford Rangers in the United States, Canada, and Mexico don't use the same engines as the Rangers in Africa, so it isn't likely anyone here has any in-depth knowledge about those engines. However, diagnosing these kinds of issues isn't strictly engine-specific. It just helps to be familiar with them. There is (or was) a really good Ford Ranger/Mazda BT50 forum based in South Africa. There are also several 4x4 websites in South Africa where people may be more familiar with the common problems found on those Rangers. I would also suggest searching for forums in Australia and New Zealand. I think they used the same engines in the Rangers and BT50.