After much research and replacing all the motor & transmission mounts I discovered the solution. "Exhaust Hanger Replacement." Wait till you see what Toyota is charging for these little babies. Essentially there are 5 hangers. Front, mid and front muffler hangers are all permanently attached to spindles and a small metal hanging chassis. Replacement is easy and can be done with just a socket wrench. The local dealer here charges $63 a piece (without installation) and $12 for the rear muffler hanger. If you could just replace the rubber the entire job would cost less than $10...But No!! By just replacing the mid and front hanger I eliminated 60% of the annoying vibration. After replacing the remaining 3 I had a brand new 95 Camry.
Rough Idle/Vibration when stopped in drive If I put in Neutral its smooth as silk. Very annoying, have replaced the air filter spark plugs spark plug wires replace auto transmission fluid, flushed radiator, replaced PVC Valve, dog bone motor mount, and just for the heck of it the main belt for air/Generator to. Cleaned Throttle Housing with Throttle plate cleaner. Still does the same thing when in gear and stopped!!
I noticed this on my vehicle. If I shift to neutral, the vibration decreases. Articles on the Internet recommended a Top Engine Cleaning service which my dealer says they don't do anymore.
I had this problem on my 1996 Geo Prism (Corolla).
UPDATE: I've just had the top "dog bone" engine mount replaced at about 136K miles. It was pretty worn. That may have contributed to the vibration. It should have contributed to the jerky stops and starts I was starting to see.
Severe vibration when car is stopped and gear selector is in drive. Vibration increases when ac is on. Solution clean the throttle body and throttle valve and mass airflow sensor with correct chemical cleaners to get rid of carbon buildup on them. This fixed the problem. I still have slight vibration but this is not a V6 and not a new car of course. The vibrations where so strong that I thought that it was a broken motor mount but after replacing those and still having the problem I knew it was something else. Check you tube for cleaning throttle body and mass airflow sensor. This is something most people can do if you can do small repairs on cars. Good luck.