Loss of strength and greater consumption Mitsubishi L200

I have problems with a Mitsubishi L200 year 2003 4x4 Diesel, on the road it does not upload more than 105 km and in the slope it stays ends by lowering two to three changes. Cause according to my mechanic that this truck was placed a mechanical pump and is not related to the turbo that is of variable geometry. There are two solutions to place the electronic pump but we do not know that we can carry that, we do not know the reasons because it was changed. And the other solution is to place a mechanical turbo and there would improve a lot because it would be compatible with the pump. Someone can intrute me more on this subject