My other half would not be amused at me trying to take the gearbox out, (I'm on thin ice already with this car due to the amount of time and money I've spent on it, she just wants a car that works and doesn't really care what it is) let alone the fact that I have nowhere and no way of doing such a thing.The other noise sounds like a very noisy dry bearing or a bearing turning in its housing. I know autos sometimes do make a bit of noise that sounds like a bearing turning in its housing (my previous auto did at low RPM in 3rd) but it was rather loud and came and went with load as the box tried to decide what the heck it was doing. It was shuddering badly on takeoff below 15mph as well a few times although that could still potentially be plug leads. I'm still going to fit the new plug leads when they arrive, I don't have much choice.
It's not a happy bunny indeed. What I don't understand is why its so intermittent, its almost schizophrenic. When I took lexi for a drive only a week ago it would barely play up and it was almost flawless on the way home that night after doing the plugs and the manifold gasket.
If I had to guess (with my limited understanding of autos) I would say there is some problem with the main rail pressure regulation that is on a bad day allowing the pressure to drop causing either slipping of the main clutches/brakes, or difficulty in regulating the torque converter lockup clutch, or both.
It seems almost as if the ECU is constantly trying to adapt too, if I do a reset, once it has adapted (which doesn't take long) it usually works a lot better for a few days then deteriorates... perhaps the ECU adapts to the behaviour of the gearbox with a certain rail pressure, and when the pressure increases or drops from what it has learnt it fails to regulate the clutches properly...in particular the partial slip mode of the torque converter lockup clutch must require a very delicate balancing act from the ECU, and probably requires well regulated supply pressure to work reliably.
Whether the pressure is varying because the filter is blocked starving the pump, a faulty electrovalve, bad wiring to the ECU, a fault in the valve block, is anyones guess. One minor consolation may be that if the gearbox behaves more or less normally SOMETIMES, the clutches may still be ok, although too much driving with them slipping will see that situation change for the worse no doubt...there was no evidence that I could see of clutch debris in the oil I removed. (Although whether the filter would trap that and prevent it being drained I don't know without studying the circulation paths)
Time for me to break out the training manual again and read up on how the valve block, electrovalves and pressure regulation works...
which means my daily commute will change from car to train in a couple of weeks...(although it was only 2 miles a day anyway) which means I will be able to keep the driving down to an absolute minimum (fortnightly supermarket runs) while I ponder what to do about the situation... 
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but in all the years I've worked on cars I've had very little cause to change spark plugs, and never on an engine where access to them was down a long skinny tube... 
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