Severe loss of power + rattling sounds from '90 engine.   I made a short recording - the rattling is most pronounced after 6 sec,  around 8 sec there is a "clunk",  rattling is in the recording is not as noticeable after this.

http://dl.dropbox.com/u/13252992/vanagon%20engine.mp3
Any ideas what might be happening?    I'm debating whether it will be worth towing it to shop; I fear that repairs will be too costly.   Also,  any recommendations for engine repair shops  in the SF bay area?   Thanks!