Dodge Intrepid transmission problem?

I recently took a trip to Minnesota (from Indiana) in the middle of winter where it was about -10 degrees. When I was there I was having a little trouble starting my car but it eventually got going and was fine once it warmed up. But ever since I went there and have come back to Indiana I have been having trouble with my car when it tries to shift gears. Unfortunately I don't know much about cars, but whenever I'm going at a slow speed and start going (going out of a turn, just after a speed bump) my car will stop going and even though I press on the gas, the engine revs up but I don't go anywhere like I'm in neutral. It does it about 3 times each time I start my car and then it stops once I've gotten going but getting out of my apartment complex or a parking lot takes a while because it keeps stopping. Can someone help me? I checked both the transmission fluid and the oil and they both were fine. I have a '97 dodge intrepid with about 120000 miles. I dont' know the engine size of the car. Thank you for any and all help you have! :)