I have a 1996 Lumina. My car is an automatic and it takes about 2 to 3 minutes for my car to go in to gear. Once it is running it runs fine. My husband just changed the transmission fluid and filter. What else could it be

It could be the shift cable needs adjustment. Another possibility is the Transmission Range (TR) Sensor. It is mounted on the transaxle and senses the position of the gear selector, as chosen by the driver. Remember, a safety feature on most automatic transmissions is that you need to have your foot on the brake for at least 5 seconds before it will shift out of Park. It's an interlock, which also may need to be checked.

Once your husband changed the transmission fluid and filter, did he start the car and pause at each gear to allow the torque converter and transmission housing to properly fill?