Or slowly turns off.

My timing is perfect, my filter is good. all else is good.


Is this normal? I would think not. but i may be paranoid.

 

carbed or EFI?

EFI: no, that shouldn't happen. turning the key off should kill both ignition and fuel. You might be mistaking compression pulses as inertia keeps the engine going.

carb: no, but possible. turning key off only kills ignition, if there's some carbon in the combustion chamber glowing it can ignite fuel and air still being pulled in as the engine keeps being spun by inertia.

Vids might help

 

dieseling is the effect .. may want to read on that.

 

Yea google Dieseling or Run on. It should give you the causes and possible soultions.

 

Is the truck running hot? If you have an automatic transmission, shut off the engine before you take it out of gear (doesn't fix the problem, just the symptom)