2002 Saturn Vue

If it goes away when earmed up it could very well be an exhaust leak. When the exghaust heats up, the parts expand which can sometimes cause theleaks to go away. Look for any black soot where the manifolds bolt to the engine or at any connection in the system. This is a sign of an exhaust leak. You can also use an old rag to hold over the tailpipe momentarily to make the leak louder to aid in locating it, but be careful the exhaust system is hot from end to end