Having issues with my Infiniti JX35 2013 180K miles, few days ago when climbing uphill on a highway suddenly lost torque and power while pressing gas pedal.

Background:

1. Purchased with 40k miles and maintained according to manual, all services done through dealer
2. Transmission Oil was changed when vehicle hits 100K through dealer.
3. My commute 60-50 miles 4 days a week through mountains uphills and downhills.
4. Few months ago check engine popped up on a dash board and error codes related to Catalyst Converter Bank 2 low efficiency code
5. Went trough forums including this and most related occurrences are transmission or solenoids replacement
6. When car sits idle for day or two I can drive 30-50 miles and then lost of power occurs
7. Tried tiptronic shift and it seems that gear is stocked in 5th gear when going up, shifting with tiptronic not really helps, car start shaking
8. I also noticed then filling up fuel from local Gas shop for last few months triggered random check engine light, could it be related to fuel quality, I always use high octane gas
9. every 5-10k miles used fuel injection system cleaning by total tech

Questions, based on your experiences:

1. Could it be sensors?
2. Could it be failed transmission?
3. Failed Solenoids?
4. Catalyst Converter Bank sensor sending wrong data?
5. Should I go through dealer or purchase online transmission assembly with low miles?
6. Should I add solenoids to replacement list?
7. Risk buying from car-parts?


Thank you!

Welcome. Considering the mileage, I would probably think it may be transmission related and not sensor related. Particularly because of the widespread and known CVT issues in the early generation of the JX/QX that were resolved in the later years.

Thank you!