JacobT

From my experience with GS4, the hesitation comes from the tranny ECU. To test to see if your car have the hesitation problem. First bring your car to 60 mph, then slow it down to 20 mph. At this time, floor it as hard as you can, you'll see if you have the hesitation problem or not.

When you're at 60 mph, the TC is in fully locking mode and 5th gear. While slow down to 20 mph, the gear stays at 5th. When you fully open the throttle at this time, the tranny ECU needs to unlock the TC, determine your throttle position and which gear to down shift to, then do the shifting. All these need to happen fairly quick, but it takes time. That's where the hesitation comes from. IMO.

Navidf

Thanks everyone
The hesitation is not due to the cold weather and it seems to improve in the power mode. It is worse when trying to floor it from 50 to 80 (or higher) than from standing position. I am beginning to think it is the normal response for this car. I will, though, have them check the ECU number as suggested.
There is a TBS for some rattles. Check them out:
NV018-98 OCT 98 Squeak & Rattle Service Tips - Instrument Panel Area

NV021-98 OCT 98 Squeak & Rattle Service Tips - Steering Wheel Area

This info is available at www.alldata.com