Lack Of Pulling Power

[cpcoffeebean]

Recently bought a Hiace for pulling stuff, cars, small machinery etc. since getting it, it seems really down in power without anything behind it. Its had service, as in oil and filter change, fuel filter, air filter all which looked as if they had not been changed since new, but its still dead as a door nail, there is only around 135k miles on it and timing belt not done long.

Also seems to be a bit of oil in the inlet manifold, does this sound right.

Any suggestions are very very welcome!!!