Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
That sounds like an outer CV joint problem.
There has been a service bulletin for that type of concern in colder temperatures that requires that the grease be changed in the outer joints. If it does it when warmed up, (or in the warmer months) then you will want to replace the outer joint.
Here is what it states.
Bulletin No.: 08-04-19-001
Date: March 17, 2008
with V6 Engine (VINs 7, N - RPOs LY7, LZ4)
Regrease both the left and right front wheel drive shaft outer joints following the procedure listed below. Use the synthetic grease provided in the new boot kit P/N 19178957.