Help! Car stalls when going from high RPM to idle

[Ben Pearre]

Hi!

1990 200AQ.

I just drove 1300 miles without a problem.  Returning from Nova Scotia
to Boston, I stopped off in Portland to get a UHaul trailer (I'm
moving to Boulder tomorrow).  That means I towed the trailer (empty,
but lots of windage - 18 MPG @ 60 MPH, normally this would be 27 or
so) for about 100 miles.  Now, the car keeps stalling, both when I
start up and when I take my foot off the gas/hit the clutch.  The
engine comes down from 2000 RPM or whatever and just keeps sinking
lower and lower until it stalls.

Trying to start the engine, it sometimes seems to catch, but can't
hold up its RPMs, and just stops.  I can then start the car by giving
it some gas while turning the starter.

It seems to happen more when the engine isn't warmed up, but I
wouldn't swear that this is a large effect.

The car normally idles at 700 RPM or so, and that works fine.

Thanks very much for any ideas!!

-Ben

--
bwpearre at alumni.princeton.edu                 http://hebb.mit.edu/~ben