Engine speed is the primary input that determines the stiffness of the mount.
Inspect the rear engine roll restrictor for debris and install a service shield.
Andrew Markel discusses the relationship between motor mounts and U-joints, and how position changes in the engine can affect U-joints and CV axles.
In this Tech Minute, Andrew Markel discusses suspension bushings and motor mounts, and the nature of the non-oil fluid that aids their function.
Andrew Markel shows how an EVAP code and a catalyst efficiency code are both related to weak motor mounts.
Back in the old days, spotting a failed motor mount was easy. The cooling fan hit the radiator shroud and the engine would move side-to-side as the engine was loaded. Today, it takes a little more time to spot a worn motor mount. Why? Because a modern motor mount might do more than just hold the engine in place.