2016 Sorento - Engine revs high and vehicle stutturs from cold start - No error code
My wife's 2016 Sorento has an issue lately that is concerning. She no longer feels safe going any real distanct with her car.
When starting from cold (as in left over night or more), when we start the car, the engine revs high and when we put it in gear and press on the gas, initially the engine just revs highter (5000/6000 RPM) and the car stutturs forward a few times, but with seemingly no engine power. However, after running for a minute or so, the stutter seems to settle down, although the car seems to be very fuel hungry (based on the litres/100km usage)
We brought it to the dealer. They ran checks. There are no codes, and they weren't able to reproduce it.
However, the issue seems to be getting more frequent.
One thing to note, the car had an ECM upgrade done maybe 5-6 weeks ago, part of a recall (in Canada).
We are concerned that this behaviour, whatever it is, will wreck the transmission.
Any ideas what it could be?