Corolla Vibrations During Idle

[Corolla123]

My Corolla 2006 Auto SECA starts to vibrate whilst idling.

The revs are sitting around 600 in drive and are higher in n during the idle. I've done about 93000km in the car and for over a year I have witnessed a rough idle that cause the car to vibrate. The vibrations are worst when the car is in drive and they become better when the selector lever is moved into neutral. I went to my dealership with the problem and last year they changed something called an idling valve? Didn't really fix the problem and indeed I believe that they had no clue what on earth they were doing. The dealership also said something about my tachometer showing about 200rm less than the engine was actually doing. All sounds a bit fishy to me! The vibrations get worse as the rpms fall, so I think that they do have something to do with the actual speed of the engine. Any suggestions what is causing this as a modern car should not vibrate this much and how can I fix this??

[Branno]

What kind of vibrations do you mean, interior panels vibrating a little? Or a whole body vibration?

[Corolla123]

The whole thing vibrates, you can feel it everywhere back seats and front, especially in the doors when they are open.

[Branno]

Well everything vibrates when the engine is running, it just depends how frequent they are and how severe it is. Do you have the ability to record a video and post it?

[Branno]

On a scale of 0 to orgasm with a woman's legs wrapped around your steering wheel. How severe is the vibration?