1996 Ford F-250 keeps shutting off periodically

Engine Mechanical problem
1996 Ford F250 Four Wheel Drive Automatic 160000 miles

have a ford 250 diesel in which had no issues with running at all. Runs strong but recently it started to have issues with stalling when it rained. Maybe a coincidence. Truck once warmed up doenst stall. Or bog out. But now. It is not starting at all. SOmeone told us it could be a sensor fuel and then someone told us it could be electrical. Not sure where t start first. The year is a 1996 and the strong once running is a beast. And runs strong. But just like I said recently having issues