Dodge Ram 3500 Diesel check engine light is on and truck wont go faster than 55 on 2006 Dodge Charger

This happens when pulling a load.
Mechanic says that all the fuel injectors must be bad, but I am skeptical.

Asked by for the 2006 Dodge Charger
the injectors may be just dirty or you may not have it tuned for pulling a trailer as heavy as what your pulling
You can't be serious. Truly absurd.