99 regal GS transmission problem?

I have a 99 Regal GS with almost 180km on it..the last few days as I am just returning home from work (I work about 20 minutes from home highway driving) on excellerating from a low speed I hear a clunk as it is going from 1 gear to the next, not a loud clunk but nevertheless a clunk...driving around once the car has cooled down it doesn't do it...when I put it into reverse it also does a clunking noise (only when the temp outside is very cold and when the car is warm) my husband checked the transmission fluid it seemed to have bubbles on the dipstick and the smell (which I had to smell due to his lack of smell) seemed to be a burnt like smell..does anyone know what is going on???could it be I am looking for a new or rebuilt transmission with such low mileage? any suggestions would be helpful..I thought that a flush might help but have been doing some "googling" and it seems that if it is a transmission problem then it might be too late for that

Welcome to AF.

With over 100K miles I would not get a flush. When was the last transmission service - ATF replacement and screen filter?

Dextron-III has a funny smell so that is normal but should be replaced at the proper maintenance interval which is 100K miles under normal conditions or 50K miles under service like taxi, police, etc. How is the shifting from 2-3 and 3-4? Also, consider getting it scanned with a trans capable scanner and see if a P1811 DTC is stored. A common cause of hard or harsh shifting to include the clunking is the pressure control solenoid (PCS).

thanks for the response...of course since I posted on here the car has not had any issues at all...go figure..when and if it does I will try to do what you suggested and forget the flush...thanks again!!!