I have a nova 6 cyl auto it runs great but when you come to a stop it vibrates or shudders at an idle, if you shift into park or nuetral it smoothes right out . I wonder if its the torque convertor? is there any way to check. thanks alot for your help.

 

I would start by looking for a miss caused by a bad tune up or a possible vacuum leak. Running on five instead of six will cause a unbalanced effect which will result in a shudder or vibration through the drive line.
Putting the car in neutral takes the load off the engine and simply eases the vibration. Its not in your transmission.

 

Check your motor mounts too.