engine diesels no matter what

[Chevota]

i have an 81 with a 86 22r in it with a weber 38, no matter what i do every time i turn the truck off it does it, im pretty sure it only does it when i lay into the pedal but im not sure. i still have mechanical fuel pump in it.
what can i do to fix this :redspotda

[bbagwell]

Turn your idle down.

[Chevota]

it wont go any lower if i do it will idle at like 500

[bbagwell]

I have had the same problem with Webers dieseling. Turning the idle down seemed to help most of the time but it would still do it sometimes.