I have 2008 Lincoln MKX with 136k miles. There is a slipping and jerking in transmission when it changes from 1,2,3 and 4. When I stay at constant speed 30M/h it can be clear and it lets the car to shake a little bit and that always happens. After reaching 60M/h the slipping stopped.
In parallel there is a whining or whooshing sound increasing with acceleration over 30M/h and increased with speed (It sounds like airplane engine)
I have recently changed the PTU at Ford dealer because of leak issue which costs $1800 but that did not solve the problem.
I asked them to check maybe there is a misfire but they did a computer test and no misfire problem appears.
The only thing I am thinking about now is to change the TSS and OSS sensors. It will cost me $600 but there is no guarantee that this will fix the problem. Other option is to change the whole transmission unit which will cost $2500 and I do not have budget for that.
Please tell me what it could be the problem?