My TE has now decided that 2000Rpm when warm is a good place to idle, yet with a quick blip of the accelerator it slowly comes down again..

What am I looking for to stop this Problem???

Sounds like the idle controller.
Dunno about 3rd gens but on the 2nd gens there's a wiring loom/plug that goes into the T/b that, when dc/ed ups the idle to 2000 rpm constant. I think it's just a default value.
try wiggling this plug around and see if that helps, could have gotten water into the plug, or possible the idle controller is broken.

Induction bits on the V6 3rd gen look pretty identical to the bits on an AstronII 2nd gen... :confused: