Hard shifting on my transmission when I stop and take off again.
The only guess I can make with nearly zero information about your vehicle and problem is; You might need a rebuilt transmission.
what speed is the engine idling at the stop light?
Have you checked the oil level?
Would your 2002 have vacuum assist in the transmission selecting? if so I would look at the vacuum lines for any broken or disconnected or pinched. if you take a vacuum line off al older transmission it will shift hard.
Is this just a single “jolt” when you come to a stop sign, and stop while remaining in D? Perhaps followed by a similar “jolt” when you take your foot off the brakes and start moving again?
Or is it harsh shifting all the way up the normal gear shifts (1-2, 2-3, 3-4, etc) as you accelerate from a stop until you reach 30 mph or so?
Could be a bad solenoid in the transmission.