First off, consider buying your parts from this site (FastLane & PartShop). They make the information on this forum possible. By supporting their business, you're supporting this site. Besides their prices and service are first-rate.
As for your engine, if you had the 16 valve you'd know it. It's a very rare option that would make your mild mannered benz act like a sports car. The valve cover has a HUGE "2.3 16" on the top.
Here's a good example of one on Ebay:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2461977352&category=6328
Welcome to the forum, and good luck with your "new" car. It's a fantastic automobile.
Jeff Pierce