CO (carbon monoxide) poisoning happens the way it does for this reason: You don't feel lack of oxygen - you feel abundance of (uncleared) CO2. If you have too much CO, you lack oxygen but don't have too much CO2, you just feel sleepy/drowsy but suffocate and die unless you do something.

Whether the rest of OPs theory makes sense, I don't know - but this part is indeed factual AFAIK.