Stalling / Rough idle

2002 Camry; 60,000 miles. For the record, I recently had 60K service done but it's unrelated to my problem. Every once in a while car stalls in stop and go traffic or when coming to a stop. The check engine light doesn't go on. Runs OK at higher speed but stalls and quits when coming to a stop. It starts up right away but dies again at the next stop. This only happens once in a while. Last time it happened, I took it to the dealership while it had the rough idle. Of course when they checked it the next day, they couldn't replicate the problem and the computer doesn't show any problems. The dealership kept the car for three days without a successful replication so they gave me the car back without charge. However I fear that the problem is still there and will lurk its ugly head soon. Your help is greatly appreciated.