2003 Tracker Electrical failure

Hoping someone can help me here since the dealership is dumbfounded. When driving during rain, Especially on the highway the engine cuts out. It happens as soon as my speed gets to about 10 miles per hour - like when approaching a stop sign or traffic light. I can re-start but it cuts right back out. After a few hours of sitting it is driveable again until the next rain. The vehilce is still under warrently and with only 16.8K miles. Has anyone experienced the same issue ?