Possible reasons:
Transmission problems:
*Low transmission fluid level
* Worn or faulty transmission clutches
* Malfunction of automatic transmission solenoids
Problems with sensors:
*Faulty Throttle Position Sensor (TPS)
*Faulty crankshaft position (CKP) sensor
*Faulty camshaft position (CMP) sensor
* Faulty automatic transmission input shaft speed sensor
Electronics problems:
* Faulty Transmission Control Module (TCM)
* Faulty Engine Control Module (ECM)
*Wiring problems
Engine problems:
*Low compression in cylinders
* Clogged fuel injectors
* Faulty mass air flow (MAF) sensor
Diagnostics:
For an accurate diagnosis, you should contact a qualified mechanic who can perform the following tests:
*Checking the transmission fluid level
* Scan fault codes
* Visual inspection of the gearbox and electrical wiring
*Checking transmission pressure
* Testing sensors using a tester
Solution:
Depending on the cause of the problem, the solution may include:
* Replacing transmission fluid
* Replacement or repair of gearbox clutches
* Replacement of faulty sensors
*Reprogramming or replacing TCM/ECM
* Repair or replacement of wiring
* Engine repair