ZX2 engine vibration

98 2.0L DOHC automatic with just over 100K. Don't know much about this vehicle as it is my cousin's husband's car, but I was asked to take a look at a few issues. The one that I am addressing here is a very noticeable engine vibration which can be felt throughout the entire vehicle. Seems to go away above 1700 rpm. Midas told them that the right side motor mount needed to be replaced. I took a good look at it and it seems OK to me (securely mounted, rubber intact, not degraded, and is still pliable). I took the serpentine belt off of the vibration dampener and ran the engine for about 30 seconds or so and the vibration is still there. The engine seems to run just fine....... idles smoothly with no missing. Any ideas? Thank you for your time and consideration. Rob