Well I don't know about the Black smoke or running rich, but
the bucking sure sounds like Vanagon Syndrom. Check out:
http://www.geocities.com/harald_nancy/intermitt._syndrome.htm
http://www.members.shaw.ca/bilbo/WBafm.html
Thanks,
Chris

---- Original message ----
>Date: Mon, 17 Feb 2003 13:22:40 -0800
>From: Matthew Pollard <poll7356@UIDAHO.EDU>
>Subject: I just want to drive?? (fwd)
>To: vanagon@GERRY.VANAGON.COM
>
>can anybody shed any advice for this guy. reply to him, see
below.
>matthew
>
>
>
>---------- Forwarded message ----------
>Date: Mon, 17 Feb 2003 20:39:52 +0000
>From: "danoromano <danoromano@hotmail.com>"
<danoromano@hotmail.com>
>To: Syncro@yahoogroups.com
>Subject: [Syncro] I just want to drive??
>
>Hi all,
>
>I need some advice.  I was running rich in my 87 syncro.  I
started
>small on fixing things and it seemed to keep going fine
until now.
>About two weeks ago I went to drive across town to pick up
some
>stuff.  As I drove and van warmed up I had no acceleration
and it
>seemed to "hop" and everynow and again it would go fine.  I
limped
>the van home and stated to check stuff out.  With some
advice I
>cleaned all my ground wire connections, checked the air
filter and
>the little door way inside the 2 1/2 inch hose, unplugged
the oxygen
>sensor and had the temperature sensor replaced.  I went to
drive it
>again today and the same thing happend.  It started fine and
then I
>drove for about 10 min. and no acceleration, hopping and a
general
>feeling of no power.  As I was creeping home I noticed black
smoke
>out of the exhaust. Any ideas?  Is this really bad?  Do I
need a new
>engine?
>
>I have no idea where to look now for the problem.  Any help
in
>getting my van running properly again would be great.
Thanks in
>advance.
>
>Dan Romano