My stupid brain always associates the name Thirteen Ghosts with Venom (2005) and I only realized why just now, when I looked up the latter:
Summary: A group of teenagers fear for their lives in the swamps of Louisiana, chased by Mr. Jangles, a man possessed by 13 evil souls, and now relentless in his pursuit of new victims.
I only saw Venom once when I was way too young and it has its own neural pathway.
Bonus: I found Venom by searching "horror movie truck snake demon" because that's the imagery that automatically pops into my head alongside Thirteen Ghosts. It's the first result.
It's T'au heresy, I tell ya! Begone with it!