I think the ECU needs replacing, or possibly the torque converter. I have an intermittent problem with the gears engaging, but the engine seems to run fine.
You are correct about needing an ECU and possible a new transmission. Your vehicle may be covered by a recall from the manufacturer. The recall is T-CP-2TC. You will need to contact your dealer to see if your VIN is covered under this recall. The recall may replace the ECU and\or transmission assembly.
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