Earlier you wrote it was "because I was in totally the wrong gear going up a steep hill".
Now it's "Someone has messed with the fuel pump (before I owned it) and/or the throttle cable isn't adjusted properly."
Here's NJ's law:
> No person shall retrofit any diesel-powered vehicle with any device, smoke stack (i.e., hood stack or bed stack), or other equipment which enhances the vehicle's capacity to emit soot, smoke, or other particulate emissions, or shall purposely release significant quantities of soot, smoke, or other particulate emissions into the air and onto roadways and other vehicles while operating the vehicle, colloquially referred to as "coal rolling."
Did you purposely release significant quantities of soot? According to your own words, that was not your intent.
Therefore under NJ law you were not rolling coal, even though the visible effect is the same. The law is based on your intent and purpose.
Now it's "Someone has messed with the fuel pump (before I owned it) and/or the throttle cable isn't adjusted properly."
Here's NJ's law:
> No person shall retrofit any diesel-powered vehicle with any device, smoke stack (i.e., hood stack or bed stack), or other equipment which enhances the vehicle's capacity to emit soot, smoke, or other particulate emissions, or shall purposely release significant quantities of soot, smoke, or other particulate emissions into the air and onto roadways and other vehicles while operating the vehicle, colloquially referred to as "coal rolling."
Did you purposely release significant quantities of soot? According to your own words, that was not your intent.
Therefore under NJ law you were not rolling coal, even though the visible effect is the same. The law is based on your intent and purpose.