I have checked pin 5 at MAF and read 1.5V at idle. This roughly increases to 3.5V with burst of throttle. These are the values Autodata give. I will replace MAF sensor anyway and fit another throttle body if that makes no difference. Also emmission test shows lambda to be high (approx. 1.3) at both idle and fast idle. Will carry out above tommorrow morning and post results. Thanks for the response.