Ford Ranger engine hesitates/stalls when stopped

Truck has been running great lately. Recently purchased from a serviceman, who while on deployment the vehicle was parked for extended periods of time ( hence the low miles ). Has been driving fine for the past two weeks fine. When delivered the car had minimal fuel in the tank, and since then has received multiple, $10-$20 at a time fuel stops. Please note that I found multiple glass marbles around my truck the other morning, on the gas tank side. I'm hoping it's old gas or debris in the fuel. Any help would be appreciated.
Thanks,
Bobby Jones