Master Mechanic opinion Wanted 2013 Ford Fiesta

Oviedo FL

Description

I have a 2013 Ford Fiesta with seemingly some type of transmission problem. The mobile mechanic says its not the transmission. YOUR opinion is needed. 1) the transmission was flushed drained and new fluid out in. 2) the transmission control unit (new part) was replaced a few days ago (TCU) 2) the 02 sensor was replaced a few weeks ago WHY all? Originally, the car was eating gas like there was a hole in the tank (02 sensor replaced) The car started making a zzzzzzz noise and slowing to a crawl, it was determined it needed a TCU. That was replaced. NOW: its doing the same thing..zzzz noise, dropping to low speed and barely drivable (car is now parked and not being driven) Please share with me your master mechanics opinion