Your post is a week old, mebbe you fixed it, but here's another 2 cent's worth. Did you check the cat? From what I read on the BB a clogged cat can give these symptoms. There should be a plug in the downpipe that can be removed for a test. If the car runs OK with the plug out, it's the cat.

You may be unable to pull the plug, so see if the cat rattles if you can whack it with something. I have a cat sitting the the Bob's Garage Volvo Parts Department that came from a 1979 B21F, believed good. If you are anywhere near Houston, TX you can have it for shipping cost. It ain't a lightweight.

Good Luck,

Bob

:>)