I have a 2006 Magnum with the 5.7L Hemi with 80K miles. Since the weather has gone below the 30's (I live in WI) the tranny acts strange when I start cold. When I put the car in gear (R or D) the engine makes a high revving sound (although the revs do not go up) and the car will not shift out of first gear. After letting it warm up for 6-10 minutes (depending on how cold it is) the car operates like normal. I had the tranny fluid changed and that did not make a difference. Anyone else have this happening? Any ideas as to what is going on and how to fix it?

 

Although it's not a resolve for your problem reallybigschu, I can tell you that my Magnum R/T has had this problem since new. My dealer claims they haven't heard of this problem from any other customers! It seems to me like it's a fluid viscosity problem. I've had my transmission repaired three times. First for a leak, second was to change out the transmission control module and the third repair was to change out the valve body which required changing the fluid. It has also been serviced twice (fluid and filter changed) and it's still the same.
I don't know if it will work for you but I've found a way to speed up the "warm up" process. All you have to do is put the car in drive and without stopping get over 25mph in 3rd (this should allow the torque converter to lock up). I've found this gets fluid where it needs to be and after this it's good to go. The key is to not stop. Depending on your neighborhood that may not be easy. Sorry it's not a fix but it's got me through five Canadian winters.