Question

hi my son has purchased a 1986 v8 diesel silverado pickup truck .we live in nz it is now righthand drive and has 4speed auto i have just done a two hundred mile trip and towing a alloy boat all up boat/trailer 2 tonnes . the motor just did not want to rev at all and had a total dislikeing for going up hills .it has done 130000 miles and starts fine cold makes all sorts of noises idles ok better cold than hot . question do the cam lodes fall off the camshaft does the deisel pump have no advance mechanism or do they wear bad in pump the mpg is good for its age etc it is a very tidy truck that cruises along on its own nicely but it wont pull a maget of a greasey chop . i have not checked compressions yet but as it starts well and used very little oil on a previous long trip so the motor seems to be not too bad .ps a towed the same boat with a mitzy pajero 2800 deisel at 80/100 km . so the question is are we expecting too much from 6000cc v8 d or has it got some other problems.