[mary2.0]

Hey all. Just got my car back from the dealer for a bit of service.

Anyways, got the car back yesterday. Drove fine for about 30 minutes to an hour. Suddenly, I hit the gas and no go. A lot of hesitation when accelerating at low speeds. Even at high speeds punching the gas wouldn't accelerate normally, but no hesitation at least.

Took it to a muffler shop, thinking it was my o2 sensor throwing the computer out of wack. I do have ZZP downpipe installed and hadn't put the spacer on yet, so it was throwing a code. Muffler shop ran diagnostics. Loose o2 sensor. Put the spacer on, all codes were clear. Great I thought. Maybe once the computer resets or something it will drive fine?

It did drive a bit smoother for a bit. Then I got a transmission hot, idle engine notification and check engine light came on.

Great...I take it back to the dealer. Still under warranty.

My main concern is, why would this happen right when I get it back from the dealer? It has been driving fine for the past year. A few months with the check engine light on even. A little bit of hard driving on my end, but not driving like a maniac consistently like 24 hours at lemans or something.

So they say I need a whole new transmission. At 28k miles. After I get it back from them. (I'm really concerned they did something to my car.) I would think this type of problem would start off small and gradually get worse giving me time to address the issue sooner. But I don't know too much how transmission operates.

Muffler shop suggested I get a tune before taking it to the dealer just to see if it is a timing issue or something with the aftermarket downpipe, but they also said transmission could be the issue.

Should I go get my car back, do the tune? Or is the transmission just completely gone now? Parts are on back order (one customer has been waiting since October) and no loaner cars at the moment (so I have to Uber everywhere, or get a rental for a week at the least).

Thanks for any suggestions or advice you guys may have.

Edit:

Other symptoms:
Reverse would hardly move the car at all, really had to give it some gas, let off, then back on to get it moving.
Cold start and car would barely move giving it quite a bit of gas.
Once the check engine light came on, car wouldn't shift at all.
It felt like the car stalled or something when stopping (only once). Had to shift into park then back into drive to get it going.

Edit2:

Sorry if I'm a bit fussy. It just boggles my mind why this would happen right when I get my car back from the dealer. I'd hate to know if they really did do something or if I just got a bad transmission from the getgo.

Also, does anybody know what the wire that runs across the engine bay up top from the driver side to the passenger side? It's directly under the hood. The passenger side wire looked like it had been snipped.