How to backtrack and remove recurring exploit(s)?

I am finding recurring exploits in both firefox & chromium .cache folders. Whenever my computer slows down (a chronic problem has developed) I run ClamTK and invariably they have reappeared. I'd like to get rid of them for good. I don't know if they are reloading from a file elsewhere that I mistakenly downloaded in past, or if they occur from certain tabs I have open. A clear diagnostic and reverse tracking protocol would be very useful to me. I'd be happy to provide history files from ClamTK if this could be of help. The latest Ubuntu update didn't resolve the issue for me. Running ubuntu-bug linux in a terminal didn't produce any conclusive findings either.