This is a copy and paste from Geno's Garage.
A check of the low-power-complaint basics.
Following is a list of easy-to-do items the owner can perform
:- check for quality of fuel-
check for full travel of the throttle lever at the fuel pump-
check all turbo-to-intercooler and intercooler-to-intake manifold hoses and clamps for a tight fit-
check the condition of your fuel filter-
check for fuel inlet restriction-
check the condition of your air filter-
check for exhaust leaks prior to the turbocharger-
check for exhaust system restriction
for automatic trucks; check your transmission fluid level