Hi All Need some advice on egr system which i think is at fault,runs rough,hesitates,flat spot,Live data shows 02 loop switching on and off,(is this right?) which coincides with lamda going high and low 02 signal and running rougth.So points to air leak i think.Had fault codes of 16502,18001,17536 which i have cleared and not returned.Has anyone had similar probs? Sorry a bit sketchy at moment due to pressure of work Thanks Tony