Heat vegetable oil and butter in a large saucepan over medium heat. Sauté onion and bell peppers until tender, 3-4 minutes. Add minced garlic and continue to sauté 1-2 minutes more.

Add tomato sauce, diced tomatoes, tomato paste, and barbecue sauce, and stir to combine. Mix in chili powder, oregano, dry mustard, and basil. Add salt, pepper, and crushed red pepper flakes and sugar if you like.

Reduce heat to low and add pulled pork. Cover and simmer for 45 minutes, stirring occasionally. Meanwhile, cook spaghetti according to package directions; drain.

Divide pasta among wide bowls. Ladle the spaghetti sauce over it, top with Parmesan cheese and parsley, and serve.