Overdrive not functioning properly/possibly tourque lock up?

Hello everyone and hope everyone is having a wonderful Monday, My 97 Buick Lesabre overdrive is acting up and I never have this problem before. When I first start the car and drive I have no problems at all but when I sit and Idle and start driving (I do not drive at a green light like the duke of hazard) OD starts to jolt and buck. When I shift into third and get up to 45 mph and shift back the car is fine like nothing happened. It happens also when the car is sitting and I start it up no check engine lights etc. When I drive the blend doors of the A/C (when I have it on) shifts to the windshield when I drive and about 15 min the blend door shifts back to the mid vents. With the A/C on the transmission is struggling to speed up but when I shut off the A/C the car speeds up normally. I went to auto zone to have them check the computer of my car and it doesn’t give any codes for the transmission just basic codes for a gas cap etc. I do not know if the torque lock up is the problem. I check the transmission fluid and its still red and has no smell to it. I don’t want to continue driving the car to the point of damaged but I have no clue what is wrong. The car is due for an oil change next week (nearly meeting the miles for the oil change) and I would like anyone please any clarification or some information i can give to my mechanics when I take the car in and as well learning. Please and thank you

It almost sounds as though there is a problem with the AC putting too much load on the engine. The transmission is trying to help the engine by not shifting into a higher gear. The AC compressor may be the culprit.