Thanks for the replies
DJNEWK2 - I'll try your approach when all else fails. I thought that a bad cold start injector could be part of the problem. But so could be the idle control valve, the fuel pressure regulator, the old fuel pump in the back, the ignition control module, the idle control module, the fuel ditributor, and the O2 sensor (though taht's less likely, since the idle improves significantly as the car warms up, and the emissions are good) . I.e. I'd rather diagnose first at this stage rather than use new parts as a process of elimination. Eventually I might have to do what you suggest, however.
moedip - I've heard of the clogged screen problem before, and I am very eager to explore this. Since now I am dealing with a very costly part (the fuel distributor), I'd love to know how you got the screens out (would dental picks work?). Also, exactly what fuel line did you replace? The entire line from under the car?
The idea of installing a clear aftermarket in-line fuel filter strikes me as particularily smart. An added safeguard plus a diagnostic tool.
1989 560 SEL (black/black)
2001 Audi TT Roadster (silver/grey)