https://www.youtube.com/watch?v=KOLlhb4xpiY

Please have a look at the above video.

I have already replaced 2 of my engine mounts (driver's side and firewall side) but suspect the transmission mount may be cactus (it's impossible to inspect). The front looks okay (to the casual inspection), but I'm not entirely sure.

In the video I start by moving the selector back and forth between Park, Reverse and Drive. Apart from a clearly audible metallic click sound everything appears normal. Is that sound normal?

However later in the video I rev the engine hard (with my foot on the brake) in drive and reverse and there appears (at least to me) to be excessive movement.

Am I paranoid, or do you think the mount is cactus?

Have you noticed any decrease in vibration or harshness after installing new mounts?

Only slightly.

I think the transmission one might be stuffed but you can't get anywhere near it to inspect it. Even if you remove the battery and air intake, etc so the mount is exposed you still can't see the condition of the rubber.

Unlike the other mounts the transmission one is a b*tch to change. I'm going to have to bite the bullet and pay a mechanic to swap it out.

What makes it so difficult to swap that particular mount?

First you need to remove battery and plate and all the air intake (to gain access to the mounts nuts from above),.... then you need to release the centre pins of the front and rear mounts, remove the left wheel and drive axle front the transmission and then finally remove the cross member under the motor whilst supporting the engine. This all needs to be done simply to lower the motor enough so the three studs (fused to the top of the transmission) the mount is bolted onto can be cleared and the mount removed.

It's kind of involved to simply swap out a motor mount.

Certainly seems like quite a mission to swap the mount.
What has you convinced that they all needed swapping?
And what did the ones you took out look like compared to the new ones?

I've seen worse (in other vehicles) but I think the engine movement when the engine is revved is excessive. I don't think it should move that much.

Also when accelerating from zero up to around 40km/h I can feel slight shuddering via the accelerator peddle before it is completely smooth.

And when idling in drive the car vibrates. In neutral there is no vibration. What is confusing me on this point is that when in drive the car idles at around 500rpm and in neutral it idles at about 750rpm. Obviously idling at 500rpm could also be causing the car to vibrate...

It's normal for the idle in D to be lower than N or P

What kind of vibrations are there in D?
I think generally a way to test engine mounts is that if the idle is better in R than in D then the mounts are likely shot, but if the idle is the same then the mounts are likely ok.

My car also vibrates in D/R. What made it better is changing those solenoids on top of the intake manifold. The idle is still far from perfect but it is at least better than before.
What does your motor feel like to the touch when in D?
Does it have a miss or anything?

In D I can feel vibration thru the steering wheel, seat, console, etc. My passenger airbag even vibrates. I can stop it by touching it with my finger.

I'll try that test in the morning.

It does feel like there is a slight miss at 500rpm

Where exactly are the solenoids you mentioned located exactly? I'm trying to picture them in my head....

If the idle is that bad then there would be something else wrong with the car.
The solenoids are these two things on top of the fuel rail/intake manifold:
http://us1.webpublications.com.au/static/images/articles/i3/0307_4mg.jpg

Cool, thanks I'll investigate their function, etc :)

The idle should be much higher than 500rpm. You need to check out your idle speed controller.

The idle should be much higher than 500rpm. You need to check out your idle speed controller.

I agree. I replaced the idle controller 6 months ago (there is a possibility I didn't do it right).

I've heard owners should not mess with the adjustment screw. Apparently it needs to be adjusted when also hooked up to a diagnostic computer.

The tachometer is not completely accurate, and with the idle meant to be 620rpm in D I think it may not really be idling low just showing incorrectly