Hey maybe you could take your cat to the vet for a cortisone shot since a lot of people say allergies. That really seemed to work for my neighbor who has a little Russian Blue who would get everyone wet when he was snuggling on our laps.
My cat has the same problem. He will start purring and the drooling gets out of hand. I took him to the vet who said he had an overactive salivary gland which happens sometimes with felines.
You may want to check your cat closely when the drooling occurs. Sometimes cats seem to be drooling but in actuality are having allergy issues and a nasal drip problem.
They drool because their saliva glands are controlled by their hair follicles. When you move a follicle by petting, they start to drool from the interaction. It is sort of the same as Pavlo's dog experiment.
