What work did the dealer do? Why did she take it there?

This sounds like classic a "hot soak" problem, but you did not say how "warm" the car needs to be. If you drive it 10 min and then park and restart is it a problem? Does it have to sit a minimum amount of time to get the problem? For example, if it is hot and you shut of for 10 sec does it start fine or not?

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra