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- good
check for full travel of the throttle lever at the fuel pump- done
check all turbo-to-intercooler and intercooler-to-intake manifold hoses and clamps for a tight fit- done
check the condition of your fuel filter- new
check for fuel inlet restriction- pending
check the condition of your air filter- new
check for exhaust leaks prior to the turbocharger- none
check for exhaust system restriction - how? At idle it feels like normal exhaust pulses
for automatic trucks; check your transmission fluid level. done.