NHTSA Complaint #11481469 — 2017 SUBARU OUTBACK

My car had it's third transmission installed in October 2021 at 42,730 miles. The car currently has just under 52,000 miles. The current transmission is exhibiting symptoms of slipping and delayed gear engagement. The slipping is most concerning due to the unpredictable and non-linear acceleration when I press the accelerator. I don't know if a light accelerator application will give the expected acceleration or a 1-2 second delay followed by either weaker than expected acceleration or a surge in engine RPMs (up to 3,000 at times) with significantly more acceleration than expected. I also don't know if the acceleration will decrease or increase if I keep the accelerator position the same. This is especially problematic in stop and go city driving where light on/off pedal application is required. The more I'm on/off the accelerator, the less predictable the acceleration becomes. My fuel economy is also down from ~25.5 MPG lifetime average to less than 20 MPG the last few tanks. Subaru dealers have not been helpful or receptive to my concerns. All the loaners I've driven behaved as expected and had smooth, linear acceleration.