Thanks everyone for your help ,pani k i checked the fuel pressure with a gauge that connects to the end of the fuel rail ,it was fine and i changed the fillter as a matter of course ,ashcossie funny you say about the fuel because it only became noticeable again after filling with supermarket fuel ,filled up with super unleaded with tectron yesterday and its gone but the weather is cooler ,so ill keep to the same petrol until the next hot day and see ,ill let you know fingers crossed ,whats the differance between supermarket fuel and texaco etc