Heat the grill, and when it is hot, grill the corn directly over the flames for about 3 to 4 minutes per side or 8 minutes total. Turn only once, halfway through grilling. Remove and keep warm.
Place the clams on the grill rack, discarding any that have opened. Close the lid and grill until the clams have opened, about 10 minutes. Discard any clams that have not opened. Remove and keep warm.
In bowl, stir together the melted butter, smoke flavoring, and barbecue seasoning. Brush the potato skewers with the mixture, reserving the remaining butter mixture. Arrange the skewers on the grill rack, close the lid, and grill for 4 to 5 minutes per side or until done.
To serve, shuck the corn and place the corn, clams, and potato skewers on a platter. Drizzle the corn and clams with the butter mixture and serve.