Engine stalls // runs rough

[bluegorilla]

I have a 2001 Eurovan MV. It has the Passat V6 engine (or similar), I believe. Lately it has started to
* idles very rough especially when it's been off for a couple hours or more (like morning)
* the engine has become noisy - like a diesel sound, loud and throaty
* occasionally stalls
* seems to have lost power - noticeable when accelerating or climbing hills

One mechanic thought it was the Engine Coolant Temp (ECT) sensor. He replaced this ($260 parts and labor), but there is no improvement. Today he's changing the fuel filter, which he claims is clogged but also admits it probably won't solve the problem.

Any ideas? Any good VW places in Fremont/South Bay (SF Bay Area region) that you can recommend?

Any and all help is Gratefully appreciated :-)