1995 Buick Lesabre No AM radio reception

My AM radio reception is nonexistent unless I am within 4 miles of the station transmitter. When I pull the cable from the antenna and hold it in my hand I get reception. When I let go I lose the reception. The FM continues to work fine. ( Different antennae?) Reception is the same whether the cable is plugged into the antennae or not. Is the antennae bad, is it a radio problem, or is it just me? Help. Vern