John,
This sounds a lot like the problem I recently had.  The sooty plugs and
exhaust, as well as the rough running when cold are signs of a rich running
condition.  When the engine warms up and goes into closed loop, the O2
sensor will at least partially correct the mixture, and idle will smooth
out.  My problem was a failed fuel pressure regulator, causing way too rich
running.  You need to start by checking the fuel pressure at the T in the
fuel supply line.  There's some pretty good information on this in the
archives, and in Bentley.  Let me know if you need more help, I just did
mine a couple months ago.

The chugging may be related, but I think you'll need to resolve the rich
running first.

John Philcox
'85 GL
Newport, RI

----- Original Message -----
From: "John Rodgers" <jhrodgers@CHARTER.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, March 17, 2001 7:08 PM
Subject: Re: Rough Idle on cold start, Oil Smells like Gasoline

> Chad, I never did solve the problem. Just had a tune up, but still have
> rough idle on cold start. If I step on the gas when cold it feels like
> its running on three cylinders, and it runs like maybe one cylinder had
> too much fuel. After warm up it seems to idle ok. It continues to do
> this even though I just put in new plugs. One plug was particularly
> sooted - and the tail pipe is badly sooted.
>
> Something new has happened since I did the plug change thing. Today
> while cruising down the road, I noticed if I took my foot off the gas
> completely, I got this chugging action. Sort of a jerking action, like
> the engine was getting intermittent fuel, even with my foot completely
> off the pedal. Not quite sure what to make of all this. But I am sure I
> am having a fuel flow problem of some sort.
>
> Not sure where to begin on this. But any input from anyone on the list
> would sure be welcome.
>
> John Rodgers
> 88 GL Driver
>