Hello Vanagon experts!

I just bought an '87 Vanagon a couple of months ago, this is my first VW,
so I don't know much about them.  I have a rattling noise coming from the
rear left of the engine.  When I first heard it I thought it was from the
exhaust, so went for my drive (about 15 miles).  The rattle disappeared
once I started driving.  Coming home, it got very sluggish. My DH and
friend tested compression, which seems to be fine on all four cylinders,
but it loses power at higher rpms.  Also, it seems like the fan is not
working, so probably overheated.

Can't afford to take it in right now, so I'll start taking it apart
myself.  Any suggestions?  What's a good repair manual to get?

Thanks,
Sonia