I have had this sort of problem with an abandoned cat before although perhaps not to the same extent that you are experiencing it. I [i]thought[\i] the problem was a dominance issue with the "Pani" trying to establish his pecking order in his new household. He would be all love and cuddles and then he would attack me for no apparent reason. I managed to stop his behaviour by either using the water gun treatment or by lifting him by his scruff (as his mum would have) and giving him a stern talking to. He very rarely attacks me nowdays and the more I think about it the more I suspect it was a dominance issue.

I also imagine there are other reasons for this kind of behaviour. Pani was a abandoned tom and was used to being Top Cat in the area.

Good luck...