I would like to know if there is any way to get a RSS from a page that interests me, remove all google ads from it and save the result (title, post and image or image url) to a text or html file.
Maybe PHP would make the magic, I do not know... Any clues about my question are welcome!
You are on the right lines. Is just your regex needs tweaking.
$feed = file_get_contents('http://rss.slashdot.org/Slashdot/slashdot'); //get rss feed
$feed = preg_replace('`<a href="http://feedads\.g\.doubleclick\.net(.*?)>(.*?)</a>`', '', $feed); //am using ` as my delimiter
var_dump($feed); //do something interesting with your ad-free feed.