I need help please
 

Hi all I am new here, searching the web for some help. I was a farm implement mechanic for 15 years so I know a little about engines and such but these newer cars have me confused. My 18yr old niece has a 1998 Grand Am GT with a 3.1 engine that is all of a sudden running very poorly. A guy at the local tire shop where the car broke down claims that the camshaft has broken. He says this is real common on this family of engines. He also claims that the engine will need to be replaced as the lifters will come out of the bores and destroy the block when the cam breaks. They removed the front valve cover and claim that the valves towards the transmission side are not moving, This could indicate a broken cam butI think he is blowing alot of smoke as this sounds very unlikely to me. My questions arethis... Is it common for the cam to break? If so does it destroy the block? any input would be very much appreciated before I go tow this car to my house to tear down an engine. Thanks William