This is a very old thread now but, given no resolution was posted, I thought other Mk2 Fabia owners might like to hear that I found a cure for this issue on my car. Hence I had an identical problem with my 2010 Fabia htp 70; i.e. revs at idle or with clutch depressed oscillating between 1000 and 400, almost stalling on occasion. In the hope of resolving this I’d done everything suggested here, including locating and repairing the infamous split servo pipe (yes mine was split too), but like here, to no avail. However, I was able to replicate the pull the accelerator pedal up with the toe effect, also noted here, which often resulted in a temporary cure even though, strangely, there was no actual movement in the pedal. In fact, it worked just as well pushing the pedal to the side. The answer was a replacement used accelerator pedal off eBay for less than £20. All you need is a torch, and a 1/4 inch socket set with a 10mm socket. There are just three nuts and one electrical connector involved; really straightforward. And you don’t need to mess about reprogramming the ECU; just attach the replacement pedal and drive off. The engine adapts in a few minutes. I hope this helps someone.