2. Dirty transmission fluid: Dirty transmission fluid can also cause the transmission to slip and clunk. Change the transmission fluid according to the manufacturer's recommendations.
3. Faulty shift solenoid: A faulty shift solenoid can prevent the transmission from shifting properly, which can cause it to clunk and slip. Have the shift solenoid tested and replaced if necessary.
4. Worn clutch plates: Worn clutch plates can also cause the transmission to slip. Have the clutch plates inspected and replaced if necessary.
5. Faulty torque converter: A faulty torque converter can also cause the transmission to slip. Have the torque converter tested and replaced if necessary.
6. Transmission control module (TCM) issues: The TCM is the computer that controls the transmission. If the TCM is faulty, it can cause the transmission to shift improperly, which can lead to clunking and slipping. Have the TCM diagnosed and repaired or replaced if necessary.
If you have tried all of these solutions and the transmission is still clunking and slipping, you may need to have the transmission rebuilt or replaced.
