I would agree that this sounds injector-related to me, esp. the long cranking time (e.g., injectors leaking down.)

The other thought I had was, could it possibly be a bad fuel pressure regulator? I don't know this particular engine, but on the V8s at least, many techs will start with replacing this part when they see an idle problem since they go bad with some frequency, and not too expensive. On the 119 engine, there is a new and improved part which I had to get from the dealer so if you go that route, I'd recommend doing the same (i.e., get from the dealer; some aftermarket sources still carry the OLD style).

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Steve
'93 400E