Dodge durango 02

was running great has 109,000 miles. I was driving home from work heard a loud bang and the car stalled, had to pull over put it in park and it started up again, took it to a mechanic, not a scensor problem, he had it for 5 days could not find anything wrong. Now the truck stalles at random times in the middle of traffic, I pull it over put it in park and start it up again. any ideas