Causes of what you are describing are: Syncope, Partial seizures, or Episodic geriatric vestibulitis,. and others.
Syncope is a temporary episode of insufficient blood flow (and therefore oxygen) to the brain and causes symptoms that you describe. Syncope is most commonly caused by heart disease, but, tracheal collapse is also a strong possibility. These are the most likely causes of your dog's problem since your dog routinely coughs prior to the episode. Cough is common in both tracheal collapse and heart disease.
Seizures can be caused by brain tumors, chemical or toxin exposure, infectious agents that affect the brain, head trauma, and others. There is also idiopathic seizures, but these are usually seen in younger dogs. Vestibulitis is a problem of the inner ear which occurs in older patients and is of unknown cause
Im sorry to hear about your toy poodle, but I think this may just be happening because Cisco is getting old. He is a very old dog and it seems as if you have been very good to Cisco since he is so old. You must be a very good pet owner. I wish I could help you more, do you know if he has a bad leg or something? I would consult a vet.