Help - strange clicking noise

Ever since I bought my SVX (Aug. 2003), at times there is a funny little clicking noise. It seems to happen only when I am in 3rd or 4th gear, and usually happens when I let off/press on the accelerator. It also happens turning left and right when I am cruising in these gears on the back-country roads around here. However, it doesn't happen every time I let off/press on the accelerator, nor every time I turn left and right. When it does start clicking, it usually occurs once the car has been driven for about 15 - 20 minutes. It seems to be coming from the center of the car (i.e. the center console).

The clicking has been occuring a little more often lately, but comes and goes in waves. One week, no clicking. The next week, lots of clicking.

I have checked the CV boots, and they have no rips or tears, don't appear to be misshapen, and don't appear to be leaking and fluid.

When my tranny shifts from 1st to 2nd in the 1.5k to 2.5k RPM range, I can both hear and feel a "clunk clunk." If I let off the accelerator right before it shifts, it only happens about 50% of the time. I've heard that this could be a transmission mount problem. Could this be related to the clicking?

Also, when I am in 4th gear only, and cruising at 45 - 55mph, there seems to be some weight movement when I let off/press on the accelerator. I was told that this could be an engine mount problem. Could this be related to the clicking as well?

Could there be something that the previous owner dropped inside the internals of center console/stereo vicinity? Has anyone dropped anything in there before?

I just want the clicking to go away!!!

Thanks for the help.