I'll get straight to the point. In August the car was playing up which was closely followed up by an Engine Management light on the dash. Symptoms were: - Overly underpowered. - Cold air through air con despite turning the temp as high as 26! - Very rough drive with revs dropping sharply during gear change. - Alot of rev play during idle. - Fan at the front of the car would spin up extremely fast! Took the car in to the garage and we hooked it up to a diagnostics tool. It came up with the Engine Coolant Temp Sensor. So we changed it and it fixed the cold air through the air con but car was still rough and still under powered. Took it in again with the same fault. Now there were 2 things that could be changed. The Engine Coolant Temp Sensor and the Thermo Stat Sensor. So we changed the Thermo Stat Sensor too. It fixed the problems above for a very short while then I got the same symptoms again when just a couple of days ago the Engine Management light came on. Took it in and the result was Engine Temp Sensor Circ. So basically the same thing. Gonna go through the whole car again incase it's a faulty sensor but could it be something we've missed? The Air Mass Sensor & EGR Valve has been already changed in May so surely can't be that. One other thing, recently I noticed a pattern with the car. During idle, the engine coolant temperature will slowly rise to 90, then the car will make a distinctive judder and the rev line will start bobbin up & down and that the same time the temperature will hit 0 (60). Friend at the garage said that it seems like it's saying that too much power is being fed to it. The fan at the front of the car still also spins up EXTREMELY fast despite the air con being off or on econ. Sorry for the story, i've tried to keep it short but it's as if were coming out of ideas Please help!