Adjust your TV/Kickdown cable. If it's not the sole cause of the problem i'm willing to bet it'll help. This mechanism is located on top of your throttle body.
To adjust the TV cable you:
1: Push in and hold the release button
2: While holding in release button, push "conduit" in as far as it will go
3: Release button
4: Rotate throttle to WOT, some people do this with the gas pedal. Others do it from the engine compartment.
5: Hold at WOT for a few seconds, cable should ratchet out a click or two.
6: Your TV cable should now be properly adjusted, take it for a test ride.
Here is another post about it on NAXJA
http://www.naxja.org/forum/showthread.php?t=1015963