Overfuelling on tick over

[The Lang-Shankit Scunner]

Hi ma truck seems to overfuel on tick-over, is there anything i can do to stop it? If im driving its clear as a bell, but if i stop for a little while on tick over it shoves out smoke as i pull away.

Any ideas? Thanks

[plumb bob]

Throttle position sensor?

[davemaxx]

does veggie surfer mean you run it on veg oil, if so run some cleaner through it, like a can of wynns deisel clean up or redex, a fuel filter full.