Car shakes when stopped and in drive but not in park?

If your car shakes when stopped in drive but not in park, it may indicate an issue with the engine mounts or transmission. Worn engine mounts can allow excessive engine movement, causing vibrations during idle in gear. Additionally, it could be related to a vacuum leak, misfiring engine, or problems with the idle air control valve. It's advisable to have a mechanic diagnose the issue to ensure safe operation.