STEP 1. Check the engine performance.
STEP 2. Compare with another same model vehicle.
STEP 3. Check the transaxle control cable.
STEP 4. Check the transmission fluid.
STEP 5. Remove the transaxle assembly from the vehicle.
Disassemble and check the transaxle assembly to check if there is a foreign material inside.Is the check result satisfactory?
Replace the transaxle assembly. Replace the failure part.