Sounds like head gaskets. My '98 Forester blew them with exactly 60K and behaved the same way when they did. Your predicament: the engine must come out for them to be replaced, and this can set you back a couple grand at a dealer. If you can spare the $ and your mechanic can somehow document that the engine is in good working order, you'll have a low mileage Subaru with the improved head gaskets that should render the issue moot. Whether you can recoup all you put into it I can't say (mine was under warranty, thankfully).
