Stalled

[Ptown John]

My drive to work is only a few miles from my garage to the office garage. Of that, it is about 2 miles of suburban streets, and 3 miles of highway. This morning I got off the freeway and came to a stop at the stop light, depressed the clutch, the tach dropped as normal, wavered a bit and then died.
This has happened once before - about a month ago, similar situation but driving home. got off the freeway, second stop light, died. Both cases were at a slight incline, after exiting freeway. No unusual driving, fast or stop and start - just straight 55-60mph.
The car is a 95 993 with 30,000 miles on it. Full service history and the 30,000 tune up was done at 28,500. She has never stalled or had any problems that I am aware of, I am the third owner. She is my daily driver.
The first time it happened, it was in the midst of a very heavy downpour of rain and did not happen again so I wrote it off to rain gremlins... this morning was damp but only misting at worst...
The shop says that if I can't reproduce the problem, they likely will only be "chasing their tails" Any help is appreciated!!