986 S problem at idle, engine won't rev and shakes, battery disconnected

[Gorthaur]

Hey guys don't get me wrong, I really appreciate your help and I'll certainly push her out and try to follow your suggestions. I just made the long story short but now it's worth telling you I haven't taken the car to the PD because of their behaviour in this circumstance as well as in others. Their first suggestion was to come to my garage and install a new MAF without even running a diagnosis for more then 1000 €... And two weeks earlier they wanted to charge me with a 1000+ € bill for a cluster replacement while it was just a poor 7 € bulb...