I wouldn't worry too much about the engine wiggling around. The thing that really tells you if the mounts are shot is to put it in drive, neutral and reverse. If there's a big difference in the vibration between the three, you probably need new mounts.

By "big" vibration, I mean one position will feel pretty good but another will have a deep, resonant vibration. Most often, reverse is the smoothest because the engine is rarely torqued in that direction.

On my car, I replaced both mounts and then, about 2 years later, the right mount again needed replacing. I left the other one alone at that point.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250