I'm not even convinced "couldn't of" is incorrect. I've read that all my life.
Either way, being southern, i put emphasis on syllables differently than you do.
If I may indulge a moment of grammar fascism -
"couldn't of" has two difficulties. The first, lesser one is the contraction of "could not".
The second, greater one revolves around the observation of verb structure. You need the auxiliary verb "have" to build a correct instance of the passive aspect. "Of" is a phonetic stand-in, but it's understood that if one is writing grammatically sound sentences, "have" is the intended correct form for which the misappropriated preposition is standing in.
Finally, "stole" is, while a widely-used regionalism, not a strictly permissible substitute for the participle "stolen".
Ordinarily i do not indulge my passion for grammar and syntax. It's something of a bottomless rabbit hole, and I have no need to feed that particular facet of my muffin-topped ego.
But since I'm interpreting your post as a question as to correctness ... in this instance I am loosing my reins to hold forth upon this topic.
While I know what you mean with "couldn't of stole", the single correct formulation is "could not have stolen". Back to a cheeseburger,
The Hunt for Red October and a 24 of Sierra Nevada "Torpedo" for this bear.