Quite easy, you can change this in Admin/Content Syndication. The length is now limited to 0, change that to 1 for the complete introtext, or to the number of characters you like.
If you want to parse a RSS feed in a portal block: I'm afraid you'll only get the titles...
Dutch Geeklog sites about camping/hiking:
www.kampeerzaken.nl | www.campersite.nl | www.caravans.nl | www.caravans.net