fuel problem (starvation?)

Hi all,
I'm trying to solve a fuel / ignition problem in my '87 5000S Quattro.
About 6 months ago I bagan having hesitation problems, hard starting,
weak engine until warmed up (only the first minute or so), and a smelly exhaust. It's gotten progrssively worse, and now runs with a high idle as if the mixture is very lean.
I've replaced the oxygen sensor and fuel flter, and last year the fuel pump went so I doubt its that. I've tested the mass air flow potentiometer, and the flapper moves freely. When I bought the car seven years and 250K miles ago I replaced the fuel differential pressure regulator. Does anyone suppose that this is the problem? Or does it sound like something else?
Thanks, Jaz
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On Mon, 8 Sep 2003 20:05:45 -0500, "Stephen Clark" <nospam> wrote:

Nope -- I haven't changed it... just welded up various breaks in the exhaust over the years. Are there any tell tale signs of Cat failure?
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1) Sulfur smell or visible emissions from tailpipe.
2) Rattling sound from loose substrate.
3) Failing emissions test with high NOx.
4) General poor starting and running characteristics from incorrect back pressure.
5) Poor gas mileage.

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