Car shuts off at idle

1998 Cadillac Seville STS 91,000 miles. My car shuts off when I'm at a stoplight or idling in traffic. I turn the key and it starts right up but will happen again a couple of more times that day. I noticed this happens mostly after it rains or snows outside. But it has happened other times too. The car drives fine and no loss of power or anything, no smells, no weird sounds. The radio and lights still work when this happens. No trouble codes have come up and the check engine light hasn't come on. I was told it could be the idle speed control sensor or crankshaft position sensor, but i'm looking for a second opinion.