Stray Cat Behavior

A stray male cat has been living outside my house. The vet estimates that he is between 3 and 4 years old. I've taken him to the vet to be tested for disease and to be neutered. He is a very sweet cat and loves to be pet. However, every so often, he will bite me so hard that he breaks the skin. Sometimes this occurs when I've been petting him, but today I was just sitting there and he bit me. Then he hisses and runs away. Why is he acting in this manner? Is there something I can do to end this behavior? Other than that he is really very cuddly and purrs so loud whenever he is pet. I want to help him in anyway I can, but I can have him keep biting me. Please help.

"Love me, love me, love me --
ENOUGH!!!"

Some cats have a time limit for being petted, even though they enjoy it very much up to the point that they get overstimulated. See the "Aggression Triggered by Petting" section of the cat agression article: http://www.thecatsite.com/cat_behavi...?a=aggression2

One suggestion is to have a timer handy and watch the cat closely during your next few petting sessions. Monitor the cat's body language for signs of mood change; especially if the tail starts twitching, which usually signals growing annoyance. Track how much petting time goes by until the cat turns aggressive. You'll then have a good idea of the cat's tolerance for petting ("Okay, it's been 2 minutes and his tail is starting to twitch - that's about it for the petting...").